WILKINS, J.

The defendant, in his appeal from numerous convictions, principally challenges the lawfulness of a search conducted pursuant to a search warrant. He asserts that the affidavit presented in support of that search warrant failed to establish probable cause to issue it. The search produced substantial amounts of stolen property that led to the several indictments on which the defendant was convicted. We conclude that, under controlling principles announced by the Supreme Court of the United States, the search was unreasonable in violation of the Fourth Amendment to the Constitution of the United States because there was no demonstrated probable cause to issue the search warrant. We thus reverse the convictions.

About noon on September 11, 1980, Lieutenant Beland of the Yarmouth police department assisted in the execution of a search warrant for a room at the Snug Harbor Motel in West Yarmouth. The search warrant mentioned one Kelleher. The police found various items, some containing the name of one Pendergast whose premises had been burglarized earlier that month. In the middle of the afternoon, Beland received a telephone call from an unidentified woman who, according to Beland's affidavit in support of the warrant, said that "a motor home full of stolen stuff [is] parked behind #5 Jefferson Ave., the home of [the defendant] and his mother." The affidavit, the significant portions of which appear in the margin, sets forth the conversation further. The informant described the stolen items generally and said that the defendant was going to move the motor home because Kelleher's motel room had been raided. She said the defendant had purchased the stolen items from Kelleher. She said she had seen the items, although she did not state when and where she had seen them. In further conversation, she agreed to Beland's suggestion that she was Lynn Alberico, a former girl friend of the defendant. Later that day Beland went to 5 Jefferson Avenue and saw a motor home parked on the premises. He then prepared the application for a search warrant, obtained the warrant while other officers watched the premises, and, with four other officers, executed the warrant on the evening of the same day. Numerous items were seized in the course of searching the motor home.

The defendant filed two motions to suppress the evidence seized at the motor home. A Superior Court judge heard and denied the first motion, filed with respect to charges set forth in an initial group of indictments. When further indictments were returned involving additional charges against the defendant, he filed another motion to suppress. A second Superior Court judge heard that motion and denied it. The judges' findings concerning the issuance of the warrant to search the motor home were substantially the same.

At the trial before a third Superior Court judge, Kelleher testified to his participation in breaking and entering certain homes with one Jimmy Ellis. He testified that the defendant served as a lookout and that the defendant paid him for the stolen objects which were taken to the motor home. The defendant sought unsuccessfully to obtain immunity from the trial judge for Jimmy Ellis. The defendant asserted that Ellis would testify that the defendant had nothing to do with the house breaks at the Pendergast residences and that Kelleher had disposed of the stolen property after dropping Ellis off at his house. We turn first to the defendant's challenge to the search warrant.

1. This case was argued before us in January, 1983, in terms of the application to this case of principles expressed in Aguilar v. Texas, 378 U.S. 108 (1964), and Spinelli v. United States, 393 U.S. 410 (1969), concerning search warrants issued on the basis of disclosures by unnamed informants. On June 8, 1983, the Supreme Court of the United States decided Illinois v. Gates, 462 U.S. 213 (1983). The opinion of the Court in the Gates case, joined in by five Justices, states that the existence of probable cause to issue a search warrant should be determined by considering the "totality-of-the-circumstances" shown in the affidavit in support of the issuance of the warrant. Id. at 238. In so stating the standard to be applied where an affidavit relied on an informant's tip, the Court repudiated overly technical interpretations of the "two-pronged test" generally understood to be applicable under that Court's opinions in the Aguilar and Spinelli cases. The "two-pronged test" required that the magistrate be informed of (1) some of the underlying circumstances from which the informant concluded that the contraband was where he claimed it was (the basis of knowledge test), and (2) some of the underlying circumstances from which the affiant concluded that the informant was "credible" or his information "reliable" (the veracity test). Aguilar v. Texas, supra at 114. If the informant's tip does not satisfy each aspect of the Aguilar test, other allegations in the affidavit that corroborate the information could support a finding of probable cause. Spinelli v. United States, supra at 415.

In the Gates opinion, the Court noted that "veracity" and "`basis of knowledge'" are highly relevant in determining the value of an informant's disclosures, but it rejected the idea that these were "separate and independent requirements to be rigidly exacted in every case." Illinois v. Gates, supra at 230. "[A] deficiency in one [prong] may be compensated for, in determining the overall reliability of a tip, by a strong showing as to the other, or by some other indicia of reliability." Id. at 233. As the Court viewed the matter, "[t]he task of the issuing magistrate is simply to make a practical, commonsense decision whether, given all the circumstances set forth in the affidavit before him, including the `veracity' and `basis of knowledge' of persons supplying hearsay information, there is a fair probability that contraband or evidence of a crime will be found in a particular place. And the duty of a reviewing court is simply to ensure that the magistrate had a `substantial basis for . . . conclud[ing]' that probable cause existed. Jones v. United States, 362 U.S. at 271. . . . We are convinced that this flexible, easily applied standard will better achieve the accommodation of public and private interests that the Fourth Amendment requires than does the approach that has developed from Aguilar and Spinelli." Illinois v. Gates, supra at 238-239. In view of this new standard, said to be "flexible" and "easily applied," like some commercial product, this court issued an order on June 30, 1983, asking for supplemental briefs and further oral argument in light of the Gates opinion. It is not clear that the Gates opinion has announced a significant change in the appropriate Fourth Amendment treatment of applications for search warrants. Looking at what the Court did on the facts before it, and rejecting an expansive view of certain general statements not essential to the decision, we conclude that the Gates opinion deals principally with what corroboration of an informant's tip, not adequate by itself, will be sufficient to meet probable cause standards. The Court granted that the affidavit in the Gates case "might well not permit a sufficiently clear inference regarding the [anonymous informant's] `basis of knowledge'" ( Illinois v. Gates, supra at 246), but concluded that corroboration of details in the tip, including prediction of the defendants' future conduct, was sufficient to warrant a finding of probable cause. In this respect, the Court's treatment of the information disclosed was similar to the treatment of the informant's information in Draper v. United States, 358 U.S. 307 (1959), where the accurate prediction of the defendant's future, seemingly innocent conduct provided a substantial basis for crediting the informant's hearsay information.

We do not view the Gates opinion as decreeing a standardless "totality of the circumstances" test. The informant's veracity and the basis of his knowledge are still important but, where the tip is adequately corroborated, they are not elements indispensable to a finding of probable cause. It seems that, in a given case, the corroboration may be so strong as to satisfy probable cause in the absence of any other showing of the informant's "veracity" and any direct statement of the "basis of [his] knowledge." We shall analyze the affidavit in support of the application for a warrant to search the defendant's premises in light of our view of the Gates opinion, mindful that we should not have a "grudging or negative attitude . . . towards warrants" ( United States v. Ventresca, 380 U.S. 102, 108 [1965]), that we should pay, great deference to the magistrate's determination of probable cause ( Spinelli v. United States, 393 U.S. 410, 419 [1969]), and that a "practical, common-sense judgment [is] called for in making a probable-cause determination" ( Illinois v. Gates, supra at 244).

Prior to the Gates opinion, we might have been inclined to go directly to the veracity test and to pass by the question whether the informant's statements adequately show underlying circumstances from which she concluded that the evidence being sought was in the motor home. But the Gates opinion teaches us that a strong showing as to one element of an informant's tip may compensate for a deficiency as to the other. Illinois v. Gates, supra at 238-239. Thus we discuss the affidavit as to the informant's "basis of knowledge."

The basis of the informant's knowledge that stolen property was in the defendant's motor home is not forcefully apparent in the affidavit. She said that there was stolen property in the motor home and described it generically. Although she said that she had seen the stolen property, she did not say that she had seen it in the motor home or where or when she had seen it. From her statement that the defendant was planning to move the motor home because Kelleher's motel room had been raided, one may reasonably infer that she believed the stolen property was then in the motor home. But we do not know why she believed the property was there — from hunch, from personal observation, or from information from some undisclosed third party. The "basis of knowledge" element might qualify for a passing mark from a benevolent grader, but the strength of this element is not sufficient to bolster deficiencies in the affidavit in other relevant aspects.

We turn then to the veracity element, the question whether the information given was likely to be accurate. None of the common bases for determining the credibility of an informant or the reliability of her information is present here. The affidavit does not assert that the informant should be believed on the basis of her past performance as a credible informant. See McCray v. Illinois, 386 U.S. 300, 303-304 (1967); Commonwealth v. Vynorius, 369 Mass. 17, 21 (1975). Nor does the affidavit show that the informant was credible or her information reliable because she made a statement against her penal interest, such as admitting participation in a crime. See United States v. Harris, 403 U.S. 573, 583 (1971) (plurality opinion); Commonwealth v. Vynorius, supra. Cf. Commonwealth v. Alessio, 377 Mass. 76, 82 (1979) (no substantial weight given to incriminating statements of an anonymous informer). Nor was the informant "an ordinary citizen" who provided information as a witness to a crime. See Commonwealth v. Bowden, 379 Mass. 472, 477 (1980).

The informant's tip disclosed no other basis for reasonably concluding that she was credible or her information reliable. She was an anonymous informant, and her unverified assent to the suggestion that she was Lynn Alberico does not take her out of that category. Her concern, first expressed, that the defendant would kill her if he knew of her telephone call, casts doubt on the veracity of her admission as to who she was. A statement by a known informant who gave information placing herself in personal danger would have had far greater inherent reliability. Lieutenant Beland did not state that he recognized the voice. She declined to give her address or telephone number. Her adoption of the suggestion that she was Alberico could easily have been a convenient cover for her true identity.

Our inquiry does not cease, however, when the credibility of an informant or the reliability of her information is not shown by her past actions or by her statement itself. An informant's tip may be corroborated, and thus made trustworthy, by other information presented in the affidavit. See Illinois v. Gates, supra at 237-238; Spinelli v. United States, 393 U.S. 410, 415-418 (1969); Commonwealth v. Kaufman, 381 Mass. 301, 303 (1980); Commonwealth v. Genest, 371 Mass. 834, 837-838 (1977). The corroboration must be "weighty enough to establish reflexively" that the informant was trustworthy or that the assertions of criminal activity were well buttressed. Commonwealth v. Kaufman, supra. See Draper v. United States, 358 U.S. 307, 312-313 (1959) (warrantless arrest and search). Thus the corroboration of major parts of the informant's information in the Gates case warranted the magistrate's probable cause determination by providing a substantial basis for crediting the hearsay. See Illinois v. Gates, supra at 243-246. Corroboration of innocent details will normally be less significant in establishing probable cause than corroboration of facts suggestive of criminal conduct. See Ker v. California, 374 U.S. 23, 36 (1963); Commonwealth v. Kaufman, supra at 303 n. 2; Commonwealth v. Alessio, 377 Mass. 76, 81 (1979); Commonwealth v. Stevens, 362 Mass. 24, 28 (1972); 1 W. LaFave, Search and Seizure § 3.3, at 557-558 (1978). However, "the degree of suspicion that attaches to particular types of noncriminal acts" is said to be more significant than whether the particular conduct was "innocent" or "guilty." Illinois v. Gates, supra at 243 n. 13. A tip, intrinsically insufficient and insufficiently corroborated, may nevertheless be considered in the total picture and may contribute toward satisfying a magistrate as to probable cause. Commonwealth v. Kaufman, supra at 303. See Spinelli v. United States, supra at 418; Commonwealth v. Boswell, 374 Mass. 263, 268 (1978).

The affidavit did contain some corroboration of the informant's information. She was correct in stating that Kelleher's motel room had been "raided." This information was timely. It may reasonably be inferred that certain property stolen in recent housebreaks had not been recovered in Kelleher's motel room. Lieutenant Beland confirmed that an apparently movable motor home was parked at 5 Jefferson Avenue, the defendant's premises. The informant also seemed to know that Lynn Alberico had been a girl friend of the defendant, a fact Beland could confirm from his own knowledge. No other fact stated by the informant was corroborated. The affidavit contained no independent information in support of the issuance of the search warrant, such as a police investigation showing that stolen property was probably in the motor home or that there was a link between the Kelleher motel room and the defendant.

We conclude that the limited police corroboration of the informant's statements set forth in the affidavit and the informant's statements themselves did not warrant a finding of probable cause. The fact that the defendant had had a girl friend named Alberico added almost nothing to bolster the trustworthiness of the informant's statements. The presence of the motor home at 5 Jefferson Avenue was confirmed, but that fact related to innocent, nonsuspicious conduct. The mere confirmation, as would be true in every case, that a place to be searched in fact exists does little to credit other facts an informant discloses. Finally, the reliability of the informant's tip cannot be inferred solely from the fact that she knew that the police had raided a third person's motel room. Our cases upholding the reliability of an anonymous informant's tip have involved more substantial corroboration than that shown in this case. See Commonwealth v. Alessio, 377 Mass. 76, 80-82 (1979); Commonwealth v. Genest, 371 Mass. 834, 837-838 (1980); Commonwealth v. Avery, 365 Mass. 59, 62-64 (1974) (warrantless arrest); Commonwealth v. Anderson, 362 Mass. 74, 76-77 (1972). The facts corroborated in the Gates case are far more extensive and significant than the facts corroborated in this case. The tip in the Gates case involving the defendant's suspicious conduct, specifically detailed, was "corroborated in major part" by police investigation. See Illinois v. Gates, supra at 243. No arguably suspicious conduct of the defendant in this case was corroborated. Indeed, the informant gave little specific detail at all.

If the affidavit in the case before us were to be upheld, the Fourth Amendment would be weakened to the level of permitting the search of any person's premises based on a telephone tip from an anonymous informer who told a story connecting those premises with the fact of a recent police search of a third person's room on premises to which the public had access. Until advised to the contrary, we believe the Gates opinion should not be read as permitting such a radical result. The motions to suppress should have been allowed.

Because we conclude that the evidence seized pursuant to the search warrant should have been suppressed by application of Fourth Amendment principles expressed by the Supreme Court of the United States, particularly and most recently in Illinois v. Gates, we need not consider whether the search violated the cognate provisions of art. 14 of the Massachusetts Declaration of Rights or, if it did, in what circumstances, if any, we would conclude that that evidence must be excluded as a matter of State law.

Clear lines defining constitutionally permissible conduct are most desirable to guide the police, magistrates, prosecutors, defense counsel, and judges. If we have correctly construed the significance of Illinois v. Gates, the Fourth Amendment standards for determining probable cause to issue a search warrant have not been made so much less clear and so relaxed as to compel us to try our hand at a definition of standards under art. 14. If we have misassessed the consequences of the Gates opinion and in fact the Gates standard proves to be unacceptably shapeless and permissive, this court may have to define the protections guaranteed to the people against unreasonable searches and seizures by art. 14, and the consequences of the violation of those protections.

2. The Commonwealth argues that, if the search warrant was defective, the search was based on probable cause and could properly have been conducted without a search warrant because there were exigent circumstances justifying prompt action. Even if a warrant is invalid, a search might be justified as a warrantless search. See Commonwealth v. White, 374 Mass. 132, 140 (1977), aff'd by an equally divided Court, 439 U.S. 280 (1978).

There is a possibility that there was probable cause to search based on additional information not set forth in the affidavit in support of the search warrant. The police officer at the site noticed the defendant and his brother removing items from the motor home and taking them to the house. He also saw thick smoke coming out of a chimney although it was not a cold day. See n. 8 above for additional information bearing on probable cause not disclosed in the affidavit. Even if there was probable cause to search, the search was a general search, purportedly pursuant to the warrant, producing items not in plain view. It is questionable whether such a general search could be justified as a warrantless search. See Commonwealth v. Young, 382 Mass. 448, 460-461 (1981). Moreover, it is doubtful that there were exigent circumstances requiring immediate action. The standards as to exigency are strict, and the Commonwealth had the burden of proof. See Commonwealth v. Huffman, 385 Mass. 122, 124-125 (1982). From their testimony, the police who were on the scene while the warrant was being sought appear not to have reacted to the smoke as if it created an emergency. They waited for the search warrant. The Commonwealth did not advance the argument that there were exigent circumstances in either of its memoranda filed with the motion judges. Because this contention was not presented to the motion judges, the argument comes too late. See Commonwealth v. Scala, 380 Mass. 500, 510 (1980). The necessary factual determinations concerning exigency were not made and should have been sought when the motions were considered. Nor, as far as appears, was the defendant given warning that the Commonwealth was relying on exigent circumstances to justify the search. If the defendant had had notice of this contention, he might have offered evidence tending to show that there was no emergency.

3. Although the motions to suppress the evidence seized at the defendant's home should have been allowed and, therefore, that evidence will not be admissible at any retrial of the defendant, there was other evidence to support the defendant's conviction on at least some of the charges against him. Therefore, we consider an issue that may arise if the defendant is to be tried again.

The defendant challenged the denial of a judicial grant of use immunity to one James Ellis who, it was argued, would contradict the testimony of Richard Kelleher incriminating the defendant. Kelleher was an important Commonwealth witness. He testified that the defendant drove Ellis and him to certain houses which they broke into at the defendant's direction, while the defendant served as a lookout. Kelleher also testified that he had sold stolen property to the defendant. Kelleher's testimony tended to show that he and the defendant had been engaged during the summer and fall of 1980 in numerous housebreaks.

In the course of the trial, and after the Commonwealth had rested, the defendant moved that the judge grant use immunity to Ellis. The judge held a voir dire on that motion. He heard testimony from Ellis, who was represented by counsel. Ellis described the circumstances that led him to appear at the trial at the defendant's request. He said that he wanted to give his version of what happened concerning certain housebreaks and stolen property. However, he declined to testify about particular events, relying on his right against self-incrimination under the Fifth Amendment. He did not refer to his right, stated in art. 12 of the Massachusetts Declaration of Rights, not to be compelled to furnish evidence against himself. He testified that he had talked to an investigator for the defendant before the trial began and told him "what [his] position was in the case."

Defense counsel made an offer of proof concerning Ellis's anticipated testimony. He would have testified that he engaged in certain housebreaks with Kelleher, that Kelleher did not want him to know with whom he was dealing in disposing of the stolen property, and that the defendant did not drive them to the houses they broke into. Ellis would also have testified that he had no contact with the defendant prior to or after the housebreaks. The judge denied the motion in the exercise of his discretion.

We recently rejected the claim of defendants that they had a constitutional right to have a prospective defense witness immunized. Commonwealth v. Curtis, 388 Mass. 637, 643-645 (1983). We recognized that the Federal courts have generally rejected such claims under the Constitution of the United States. Id. at 644-645. See United States v. Thevis, 665 F.2d 616, 639 (5th Cir.), cert. denied, 459 U.S. 825 (1982). See also United States v. Bounos, 693 F.2d 38, 39 (7th Cir. 1982) ("no such animal as judicial immunity" exists); United States v. Hunter, 672 F.2d 815, 818 (10th Cir. 1982) (courts have no power independently to fashion witness use immunity under the guise of due process). The Court of Appeals for the First Circuit has left open the question when, if ever, due process may require immunization of defense witnesses. United States v. Flaherty, 668 F.2d 566, 582-583 n. 6 (1st Cir. 1981). The Court of Appeals for the Second Circuit would foreclose all inquiry into the question of immunity if the prospective witness is an actual or potential target of prosecution. See United States v. Turkish, 623 F.2d 769, 778 (2d Cir. 1980), cert. denied, 449 U.S. 1077 (1981). This was essentially the view we expressed in the Curtis case, barring "some unique circumstances." Commonwealth v. Curtis, supra at 645-646.

In passing on a request for immunity, if the prospective witness relies on his right not to incriminate himself expressed in art. 12 of the Declaration of Rights, consideration might have to be given to the requirement under the Constitution of the Commonwealth that a grant of immunity must be a grant of transactional, and not merely use, immunity. Attorney Gen. v. Colleton, 387 Mass. 790, 795-797 (1982). Emery's Case, 107 Mass. 172, 185 (1871). The situation is different under the Fifth Amendment to the Constitution of the United States, where a grant of immunity to a witness is constitutionally adequate if it proscribes the use in a subsequent criminal case against the witness of the compelled testimony and any evidence directly or indirectly derived from that compelled testimony. Kastigar v. United States, 406 U.S. 441, 453 (1972). This difference may be significant in weighing the government's legitimate interests in whether immunity should be granted.

On the record in this case, a judicial grant of use immunity to Ellis was not required under constitutional principles. We decline to speculate on what arguments on the immunity question the defendant may present if the defendant is to be retried. We would expect that any claim for immunization of Ellis would be advanced and heard sufficiently before trial so that a timely decision could be made.

4. The judgments are reversed and the verdicts set aside. The orders denying the defendant's motions to suppress evidence seized at his residence are also vacated. Orders shall be entered allowing those motions to suppress. The case is remanded to the Superior Court.

So ordered.