McKUSICK, Chief Justice.

Following a jury trial, the Superior Court (Penobscot County) convicted defendant James DeLong of four counts of incest, 17-A M.R.S.A. § 556 (1983), which he committed upon his minor daughter. On appeal defendant argues that the Superior Court erred 1) in admitting evidence of other sexual acts between him and the victim, 2) in keeping the jury deliberating until 12:40 a.m., thereby allegedly coercing the jury into a verdict, and 3) in allowing the prosecutor to disparage the defense in closing argument. Defendant also makes an assertion of insufficiency of the evidence in regard to both the Superior Court's denial of his motion to suppress certain evidence and the jury's verdict finding him guilty of the crimes as charged.

I. Other Sexual Activity

Over defendant's objection, the presiding justice, after giving the jury a limiting instruction, permitted the victim to testify at trial to incestuous conduct of her father, defendant DeLong, beyond the four instances charged in the indictment. She testified that between her ages of 12 and 18 her father subjected her to a steady course of sexual intercourse, which occurred almost twice weekly. On appeal, defendant's sole complaint as to the admission of this evidence is that the justice erred in applying the balancing test of M.R. Evid. 403. We do not agree. An appellate court on this record has no basis for declaring that the presiding justice exceeded the bounds of reasonable discretion in concluding that the probative value of the evidence of other criminal acts was not substantially outweighed by any danger of unfair prejudice.

This court has long recognized that evidence of prior or subsequent acts similar to the charged offense is admissible for any permissible purpose other than to prove the character of the defendant to show that he acted in conformity therewith. For more than a century our case law has declared that evidence of a defendant's prior or subsequent sexual relations with a victim is admissible to show the relationship between the parties or the intent of the defendant. See, e.g., State v. Witham, 72 Me. 531, 535 (1881) (evidence of prior acts similar to charged offense admissible to show relationship between parties in prosecution for adultery); State v. Williams, 76 Me. 480, 481 (1884) (same); State v. Acheson, 91 Me. 240, 244-45, 39 A. 570, 571-72 (1898) (evidence of subsequent act similar to charged offense admissible to show intent in prosecution for assault with attempt to ravish a minor; vacated, however, for failure to give limiting instruction); State v. Berube, 139 Me. 11, 14, 26 A.2d 654, 655 (1942) (evidence of prior acts similar to the charged offense admissible to show relationship between parties in prosecution for indecent liberties with a minor); State v. Norton, 151 Me. 178, 181, 116 A.2d 635, 636-37 (1955) (same); State v. Seaburg, 154 Me. 162, 163-78, 145 A.2d 550, 551-59 (1958) (same). Cf. State v. Bennett, 117 Me. 113, 115-16, 102 A. 974, 975 (1918) (evidence of prior acts similar to charged offense admissible to show intent in prosecution for indecent exposure); State v. Buckwald, 117 Me. 344, 346, 104 A. 520, 521 (1918) (evidence of prior acts similar to charged offense admissible to show intent in prosecution for accepting money from a prostitute); State v. Morin, 126 Me. 136, 139-40, 136 A. 808, 810 (1927) (evidence of prior acts similar to charged offense admissible to show intent in prosecution for operating house of prostitution).

That long and unbroken line of precedents "is still valid today" under the Maine Rules of Evidence, which became effective on February 2, 1976. Pierce v. State, 463 A.2d 756, 761 (Me. 1983). M.R.Evid. 404(b) excludes only "[e]vidence of other crimes, wrongs or acts . . . to prove the character of a person in order to show that he acted in conformity therewith." Such evidence, however, may be admissible for any other permissible purpose. State v. Pierce, 474 A.2d 182, 185 (Me. 1984) ("If . . . the presiding justice determines . . . that the evidence is offered for a purpose other than establishing character, he may, in his discretion, admit the testimony"). Thus, evidence of defendant's continued sexual activity, including a specific prior or subsequent act similar to that charged, is admissible for several other purposes that are "probative of some element of the crime for which the defendant is being tried." State v. Goyette, 407 A.2d 1104, 1108 (Me. 1979). In the case at bar, evidence of prior incestuous acts was relevant and admissible to show the relationship between the parties that in turn sheds light on defendant's motive (i.e., attraction toward the victim), intent (i.e., absence of mistake), and opportunity (i.e., domination of the victim) to commit the crimes with which he was charged. See Pierce v. State, 463 A.2d at 761. See generally McCormick on Evidence § 190 (E. Cleary 3d ed. 1984); 2 Wigmore, Evidence §§ 398-400 (Chadbourn rev. 1979). Other jurisdictions follow this rule. See, e.g., Collins v. State, 669 S.W.2d 505, 507 (Ark. App. 1984); Elliott v. State, 600 P.2d 1044, 1047-49 (Wyo. 1979) (and cases cited therein). See generally Annot., 77 A.L.R.2d 841, 878-80 (1961).

On appeal defendant recognizes that Evidence Rule 404(b) does not bar the admission of the evidence of defendant's course of incestuous conduct with his daughter. He founds his appellate argument exclusively upon Evidence Rule 403. He fails, however, to persuade us that the presiding justice committed any error in balancing the relevant probative value of this evidence against any danger of unfair prejudice from it. As we said in State v. Wallace, 431 A.2d 613, 616 (Me. 1981):

The presiding justice has broad discretion in ruling on the admissibility of evidence challenged as unfairly prejudicial; review of such rulings focuses on whether there was an abuse of discretion. State v. Heald, [ 393 A.2d 537, 542 (Me. 1978)].

Defendant takes nothing on his first argument on appeal.

II. Alleged Jury Coercion

As his second issue on appeal defendant urges that the presiding justice coerced the jury into its verdict by keeping them deliberating beyond a reasonable hour and by then impatiently imposing a time limit. Since this issue is raised for the first time on appeal, we review for obvious error only. M.R.Crim.P. 52(b); State v. True, 438 A.2d 460, 468-69 (Me. 1981).

The length of time a jury should be kept deliberating is a matter vested within the sound discretion of the trial justice. See State v. Hodgkins, 238 A.2d 41, 42 (Me. 1968). See also Hinton v. State, 272 Ind. 297, 397 N.E.2d 282, 284 (1979); State v. Crowley, 220 Kan. 532, 552 P.2d 971, 975 (1976); Commonwealth v. Watkins, 375 Mass. 472, 379 N.E.2d 1040, 1052 (1978); State v. Anderson, 698 S.W.2d 849, 853 (Mo. 1985); Farmer v. State, 95 Nev. 849, 603 P.2d 700, 704 (1979). Whether that discretion was abused is determined by viewing the totality of the circumstances in each case. United States v. Coast of Maine Lobster Co., 557 F.2d 905, 911-12 (1st Cir.), cert. denied, 434 U.S. 862, 98 S.Ct. 191, 54 L.Ed.2d 136 (1977). Under the obvious error rule, remarks addressed to a jury after retirement warrant reversal only if the additional instruction, viewed in the context of the charge as a whole, constitutes highly prejudicial error tending to produce manifest injustice. State v. Quint, 448 A.2d 1353, 1355 (Me. 1982).

In the case at bar the jury began deliberations at 3:40 p.m. and did not reach a verdict until 12:40 a.m. During the late afternoon and evening, the jury requested further instructions on elements of the crime charged and several "readbacks" of testimony. After each of the "readbacks" the court questioned the foreman as to whether further deliberations would be useful and received affirmative answers. At 12:20 a.m., after the final requested "readback" was accomplished, the following exchange occurred:

THE COURT: . . . It's now 12:20 a.m., and, Mr. Foreman, if there are any problems with any juror who is — I'm concerned about jurors staying up too late, and I just want to make sure that you take full time for deliberations and that — but that you move forward with dispatch in view of the time. I'm concerned about the time, so that I would again — it's an important case. It's taken three days trial. It's important. We hope that we can resolve the case, and you think that further deliberations would be beneficial, Mr. Foreman?

THE FOREMAN: I do.

On appeal defendant contends that the 9 1/2 hours of deliberations created problems of exhaustion that caused the opinions of individual jurors to be overcome by the majority and that the judge's statement "to move forward with dispatch in view of the time" further coerced an already weary jury into a decision.

We disagree. When viewed in the totality of the circumstances the presiding justice's handling of the jury during its deliberations did not overstep the bounds of his allowable discretion. Although the jury was out for many hours, it acted alertly throughout the evening by requesting "readbacks" and further instructions. In addition, the foreman responded affirmatively on at least two occasions to the justice's inquiries whether further deliberations would be useful. The fact that the jurors did not at the time appear too exhausted to reach a just verdict is further evidenced by the complete failure by defendant and his counsel, who were present on the occasions when the jury returned to the courtroom, to make any objection whatever to the continued deliberations or to the justice's additional instructions. Cf. State v. True, 438 A.2d at 468 ("trial counsel's failure to object to inadmissible evidence, whether as a result of tactical decision or oversight, will itself be a consideration in determining whether the error is obvious and highly prejudicial").

Moreover, the justice's remarks about "moving forward with dispatch," viewed in context as they must be, do not appear coercive. Prior to his request that the jury move with dispatch, the justice expressed concern about juror fatigue and the necessity for jurors to take enough time for full deliberations. Further, in his remarks to the jury at approximately 10:05 p.m., the justice, while instructing the jury with a view towards encouraging agreement, also cautioned individual jurors not to relinquish their views for the sake of consensus. Looking at the totality of the circumstances, we can find no error at all in the way the presiding justice handled the jury that convicted defendant.

III. Allegedly Improper Closing Argument by the State

Defendant next contends that two remarks made by the prosecution in closing argument deprived him of a fair trial. The prosecution criticized the defense strategy to discredit the prosecutrix by calling two of her friends to testify, stating:

You heard from [name deleted], a dear friend . . . of the victim. She never knew anything about this incest. She does now. The victim's friend has been brought into it.

Defendant seasonably objected to those comments and argues on appeal that those statements seriously prejudiced his case by implying that he had an improper motive for calling those witnesses. Because the alleged error was preserved by objection, we review defendant's contention under the harmless error rule. M.R.Crim.P. 52(a). Although the prosecution's remarks were impertinent, any error was harmless because we confidently conclude that it is "highly probable that [such remarks] did not affect the judgment." State v. True, 438 A.2d at 467.

Defendant also complains, for the first time on appeal, of the following remarks by the prosecution:

Throughout this entire defense, ladies and gentlemen, you're constantly saying, well, what kind of mother is Luella DeLong? Remember, she is not on trial, and what kind of a sister is Donna? Donna DeLong is not on trial. That man right over there is (indicating). They're not focusing in on the issues of this case. They are trying to develop a smoke screen to divert your attention from the real issues when they suggest to you that Donna DeLong and Luella DeLong are at fault.

Because defendant failed to object at trial, we review defendant's contention under the obvious error rule. M.R.Crim.P. 52(b). The record shows that the prosecutor appropriately used his closing argument to review the evidence and "present his analysis in summation with vigor and zeal" by "highlighting absurdities or discrepancies" in defendant's case. State v. Smith, 456 A.2d 16, 17 (Me. 1983). Although the prosecution's argument may have "denigrat[ed] [the] defense strategy," he did so by sticking to the legal issues and marshalling the evidence. State v. McDonald, 472 A.2d 424, 426 (Me. 1984). See also State v. Collin, 441 A.2d 693, 697 (Me. 1982). We can find no error, to say nothing of the obvious error necessary for vacating the results of defendant's trial.

IV. Sufficiency of the Miranda Warnings

Defendant contends that the Superior Court justice, who denied his motion to suppress all statements he had made to the police, was clearly in error in finding that the police had complied with the requirements of Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). The issue arises only because on the three successive occasions when the police officer, before questioning defendant, read the Miranda rights from his " Miranda card," he omitted the final question on the card, "Now having all the rights in mind, which I just explained to you, do you wish to answer questions at this time?" That omission, however, was not fatal to the prosecution's use at trial of the statements that defendant made after being fully advised of his right to remain silent and to have counsel.

The Miranda case does not require that the specific final question be asked; it only requires, before a person is put under custodial interrogation, that he be fully informed of the rights delineated in Miranda and that he knowingly waive those rights. An explicit oral or written statement of waiver is not required. North Carolina v. Butler, 441 U.S. 369, 373, 375-76, 99 S.Ct. 1755, 1757, 1758-59, 60 L.Ed.2d 286 (1979); State v. Hazelton, 330 A.2d 919, 925 (Me. 1975). Whether there has in fact been a waiver of Miranda rights must be decided upon the facts of each case. See State v. Carter, 412 A.2d 56, 61 n. 4 (Me. 1980). At the suppression hearing the State had the burden of proving, by the federal standard of proof by a preponderance, that the police complied with Miranda's mandates. State v. Bleyl, 435 A.2d 1349, 1358 (Me. 1981). The police read defendant his Miranda rights three times before starting their questioning; he affirmed that he understood each right; he consented to the taping of the interview; and he responded without hesitation to the questions. After reviewing all the evidence before the motion justice, we cannot find any clear error in his factual conclusion that the State had met its burden of showing that the police had satisfied Miranda.

V. Sufficiency of the Evidence

Defendant finally contends that the evidence was insufficient for the jury to have found him guilty of the four counts of incest charged in the indictment. We cannot agree. An incest conviction is sustainable even though it is based solely on the uncorroborated testimony of the victim. State v. Frost, 315 A.2d 198, 199 (Me. 1974). While his daughter's testimony by itself would have been sufficient to convict him, her testimony was also corroborated in many respects by other witnesses. By no means can we say that no trier of fact rationally could find defendant guilty beyond a reasonable doubt. State v. Barry, 495 A.2d 825, 826 (Me. 1985).

The entry is:

Judgments of conviction affirmed.

VIOLETTE, WATHEN, and SCOLNIK, JJ., concurring.