Appellant was tried four times for the murder of his wife. At the fourth trial he was convicted of second degree murder. This appeal is from that conviction.
At the first two trials the. juries disagreed. At the third trial appellant’s counsel-, in his closing argument, told the jury that “the two previous trials have ended in mistrials.” The prosecutor immediately objected and the judge said, “I will take care of it at the time of my charge.” But instead of doing so, when the prosecutor on the following day pressed for a mistrial the judge granted it.
Defense counsel never informed the jury that the two previous juries had been unable to agree. But in the prosecutor’s rebuttal argument, and again in his motion for a mistrial, he erroneously asserted that defense counsel had so informed the jury. Though defense counsel made timely objection to the motion for a mistrial, he did not point out the prosecutor’s error.
Appellant petitioned, on the ground of former jeopardy, for a writ of prohibition against a fourth trial. This court denied the petition, but “without prejudice to renewal of the double jeopardy claim in any subsequent appeal which petitioner may take.” At the beginning of the fourth trial, the defense of double jeopardy was pleaded and overruled. We think the District Court erred.
In Downum v. United States, 372 U.S. 734, 736, 83 S.Ct. 1033, 10 L.Ed.2d 100 (1963), the Supreme Court said: “At times the valued right of a defendant to have his trial completed by the particular tribunal summoned to sit in judgment on him may be subordinated to the public interest — when there is an imperious necessity to do so.” (Emphasis added.) Notwithstanding the constitutional prohibition against double jeopardy, the Supreme Court has found sufficient necessity for a retrial when *812a jury was unable to agree,1 or a juror was biased,2 or war conditions required postponement of a court-martial,3 or a conviction was reversed either on direct appeal4 or on collateral attack.5 But repeated trials subject a defendant to serious hardship. In Downum the Supreme Court said, “We resolve any doubt in favor of the liberty of the citizen.” 372 U.S. at 738, 83 S.Ct. at 1035.
There was no “imperious necessity” for the mistrial which the judge granted, over defense counsel’s objection, at the third trial. That there had been previous mistrials did not mean that the juries had disagreed or that the prosecution's case was weak. From references made without objection during the third trial,6 before defense counsel mentioned previous mistrials, the jury had learned that there had been at least one previous trial. The difference between one previous trial and two . is not critical. Accordingly, defense counsel’s mention of “mistrials” did not substantially prejudice the prosecution. Clearly, we think, it did not prevent a fair trial.7 The trial judge should have handled the matter as he first proposed, through a cautionary instruction.
Both the prosecutor and defense counsel are charged with conducting themselves in accordance with the objective of a fair trial. It seems likely that this objective may be more easily imperiled by misconduct of the prosecutor than of the defense, since the jury may have special confidence in the prosecutor as a public official who does not represent a biased party but an impartial sovereign whose “interest * * * in a criminal prosecution is not that it shall win a case, but that justice shall be done.”8
We need not consider whether the prosecutor would have been entitled to a mistrial if defense counsel, instead of the prosecutor, had given the jury the information that two earlier juries had been unable to agree. The prosecutor should certainly not benefit from prejudice which he himself has created.
We close with a suggestion in which Judge Tamm concurs. In retrials, references to previous trials are likely to be made. Such references may sometimes be prejudicial to the party who does not make them. We think the ultimate objective of a fair trial is most likely to be achieved if at the outset of a retrial the judge gives a cautionary instruction, as some judges in this circuit do, to the following effect: “The defendant has been tried before. [If there has been a mistrial, so state.] You have no concern with that. The law charges you to render a verdict solely on the evidence in this trial.”
Reversed, and remanded with directions to dismiss the indictment.
. United States v. Perez, 9 Wheat. (22 U.S.) 579, 6 L.Ed. 165 (1824).
. Simmons v. United States, 142 U.S. 148, 12 S.Ct. 171, 35 L.Ed. 968 (1891).
. Wade v. Hunter, 336 U.S. 684, 69 S.Ct. 834, 93 L.Ed. 974 (1949).
. United States v. Ball, 163 U.S. 662, 16 S.Ct. 1192, 41 L.Ed. 300 (1896).
. United States v. Tateo, 377 U.S. 463, 84 S.Ct. 1587, 12 L.Ed.2d 448 (1964).
. At the voir dire one prospective juror stated in the presence of the others that her husband had “served on this ease before.” During the examination of one of the witnesses, portions of the transcript of the first trial were used in cross-examination, counsel referring to “previous testimony' under oath, in this court.” Another witness, in answer to a question, referred to “that trial.”
. See Foster v. United States, 308 F.2d 751, 753 (8th Cir. 1962).
. Berger v. United States, 295 U.S. 78, 88, 55 S.Ct. 629, 79 L.Ed. 1314 (1935); King v. United States, 125 U.S.App.D.C. 318, 372 F.2d 383 (1967).