We have held that it is error to show in evidence or to tell the jury that a jointly accused defendant had been convicted or has pleaded guilty. State v. Mull, 318 Mo. 647, 300 S.W. 511; State v. Stetson, Mo., 222 S.W. 425; State v. Castino, Mo., 264 S.W.2d 372; and see 2 Wharton Cr. Evi. (12th Ed.) § 439, p. 215. So, also, have we held that evidence of the acquittal of one jointly accused is improper.

... [T]he court must always maintain an absolute impartiality in any trial, both in its remarks and in its conduct generally; it should not do or say anything which might prejudice the jury or be construed by the jury as indicating a belief in defendant's guilt or innocence. State v. Hudson, 358 Mo. 424, 215 S.W.2d 441; State v. Castino, Mo., 264 S.W.2d 372; State v. Jones, Mo., 197 S.W. 156; State v. Bunton, 312 Mo. 655, 280 S.W. 1040; Canons of Judicial Ethics, Canon 3. The need for judges to be discreet in what they say or do in the presence of juries so as to avoid appearances of bias cannot be overemphasized.

The trial court must remain wholly impartial as between the parties and it should not indicate, directly or indirectly, a belief in the guilt or innocence of the accused; counsel must be treated fairly, and the court should not so act as to humiliate or embarrass counsel. State v. Castino, Mo., 264 S.W.2d 372; State v. Montgomery, 363 Mo. 459, 251 S.W.2d 654; State v. Hudson, 358 Mo. 424, 215 S.W.2d 441; State v. Moore, Mo., 303 S.W.2d 60; State v. Jones, Mo., 197 S.W. 156; State v. Bunton, 312 Mo. 655, 280 S.W. 1040; State v. Teeter, 239 Mo. 475, 144 S.W. 445. But, on the other hand, it is the duty of the court to maintain order and decorum, to exercise a general control over the trial, to protect witnesses from abuse and intimidation, and to keep the inquiry within legitimate issues and within the applicable rules of law.

Including, State v. Wren, 486 S.W.2d 447 (Mo. 1972) — court said that it would allow prosecutor to "develop this ad nauseum"; State v. Lomack, 570 S.W.2d 711 (Mo.App. 1978) — comment on evidence; State v. Castino, 264 S.W.2d 372 (Mo. 1954); State v. Tash, 528 S.W.2d 775, 782 (Mo.App. 1975) — brief questioning by court; no prejudicial error. Cf. State v. James, 321 S.W.2d 698 (Mo. 1959) — 165 questions or 140 pages of transcript; Clear v. Van Blarcum, 241 S.W. 81 (Mo.App. 1922) — comment on evidence; State v. Hyde, 136 S.W. 316, 333 (Mo. 1911) — physician accused of poisoning patient; court said "this is as far as you can go with an honest witness" not reversible error.

Based on the rationale of State v. Fenton, supra, we do not hesitate to invoke the plain error rule. Thus, upon review of the record and the aforementioned precedents, reversal of appellant's conviction is necessitated. For comparable examples where new trials were required, see State v. Castino, 264 S.W.2d 372 (Mo. 1954); State v. Mull, 318 Mo. 647, 300 S.W. 511 (1927); State v. McCarthy, 567 S.W.2d 722 (Mo.App. 1978); State v. Fenton, supra; and State v. Stetson, 222 S.W. 425 (1920). This holding does not mean that the disclosure of a co-defendant's guilty plea is prejudicial in all instances. That determination can be made on a case-by-case basis.

It must be emphasized that defendant called Mansfield as his witness and the court's limiting instruction went to that direct examination. The testimony of Mansfield paralleled that of defendant's concerning the incident and he manifested no hostility. Under these circumstances he was not subject to impeachment by defendant, State v. Burrow, 514 S.W.2d 585, 588 (Mo. 1974); State v. Castino, 264 S.W.2d 372, 375 (Mo. 1954), and testimony of his status as an informant was inadmissible at that time. Similarly, testimony bolstering the witness whose credibility had not been attacked would not have been admissible.

It first should be noted the state may not show that a non-testifying co-indictee has been convicted or pled guilty to the same crime as that which the defendant stands charged, State v. Fenton, 499 S.W.2d 813 (Mo.App. 1973), nor may the state introduce evidence implicating only the co-indictee, State v. Mullen, 528 S.W.2d 517 (Mo.App. 1975). See also State v. Castino, 264 S.W.2d 372 (Mo. 1954). Further, Bruton v. United States, 391 U.S. 123, 88 S.Ct. 1620, 20 L.Ed.2d 476 (1968) condemned the prosecutor's introduction of an accomplice's confession by a third party implicating the defendant because defendant was denied the opportunity of cross-examining the accomplice and confrontation of his accusers.

As suggested by appellant, it is error generally to show that a jointly accused defendant has been convicted either upon separate trial or guilty plea. State v. Aubuchon, 381 S.W.2d 807 (Mo. 1964); State v. Mull, 318 Mo. 647, 300 S.W. 511 (1927); State v. Stetson, 222 S.W. 425 (Mo. 1920); State v. Castino, 264 S.W.2d 372 (Mo. 1954). However, bias or prejudice in favor of or against a party to any action may properly be shown on the credibility of the witness.

A full review of the record makes it apparent that an undue burden was placed on defendant and that he was denied a fair trial. State v. Jones, Mo., 197 S.W. 156, 158; State v. Castino, Mo., 264 S.W.2d 372, 375; State v. Sanders, Mo., 360 S.W.2d 722, 726; State v. Kimball, Iowa, 176 N.W.2d 864, 867. The judgment is reversed and the cause is remanded.

At most it indicates an attempt to require proper conduct on his part and to exercise proper control over the conduct of the trial. While the trial court must remain wholly impartial as between parties and should not indicate, directly or indirectly, a belief in the guilt or innocence of an accused, State v. Castino, Mo., 264 S.W.2d 372; State v. Pinkston, Mo., 333 S.W.2d 63, it is also the duty of the court to maintain order and decorum in the courtroom, State v. Montgomery, 363 Mo. 459, 251 S.W.2d 654; State v. Pinkston, supra, and trial courts necessarily must be invested with discretion in such matters. State v. Thursby, Mo., 245 S.W.2d 859; State v. Turner, Mo., 320 S.W.2d 579. The record does not demonstrate an abuse of discretion.