Following a jury trial appellants were convicted of violating 18 U.S.C. § 2314 for transporting jewelry stolen from a shop in Shelby, North Carolina, to Bridgeport, Connecticut. Their principal contention on this appeal relates to the extent of the district judge’s interjections into the conduct of the trial. Cf. United States v. Cruz, 455 F.2d 184 (2d Cir.), cert. denied, 406 U.S. 918, 92 S.Ct. 1769, 32 L.Ed.2d 117 (1972).
Appellants argue that the trial judge’s numerous interruptions of their counsel’s cross-examination of the principal Government witness, one Saia, prejudiced the jury against them and rendered the cross-examination ineffectual. Many of these interruptions were prompted by the district court’s duty as more than a moderator to clarify ambiguous questions and testimony for the jury and to insure that the trial was fairly conducted.1 United States v. Cur-*1207cio, 279 F.2d 681, 682 (2d Cir.), cert. denied, 364 U.S. 824, 81 S.Ct. 59, 5 L.Ed.2d 52 (1960); United States v. Brandt, 196 F.2d 653, 655 (2d Cir. 1952). Also, certain of the interruptions were “invited” by counsel’s admittedly ambiguous and repetitive questions.2 United States v. Cruz, supra, 455 F.2d at 186. We have stated that restraint is called for on the part of the trial judge to insure that he remain the dignified “personification of our legal system in the eyes of all who are present in his courtroom.” United States v. Frascone, 299 F.2d 824, 829 (2d Cir.), cert. denied, 370 U.S. 910, 82 S.Ct. 1257, 8 L.Ed.2d 404 (1962), and that he not “usurp the functions either of the jury or of the representatives of the parties,” United States v. De Sisto, 289 F.2d 833, 834 (2d Cir. 1961). We have repeatedly insisted that trial judges display patience with counsel so as not to prejudice a party or create an impression of partisanship before the jury.
But here the trial judge, despite a number of interjections, stayed within the limits this court has prescribed. None of the interventions explicitly undercut the appellants’ presumptions of innocence, United States v. Brandt, supra, 196 F.2d at 656, by implying any belief on the part of the court of appellants’ guilt. Indeed, it may be that some of his interventions helped rather than harmed the appellants’ position before the jury.3 Furthermore, the jury *1208charge properly pointed out that the court’s interventions were for purposes of clarification only, a factor that to some extent mitigates any impression created by the trial court’s interruptions. United States v. Cruz, supra, 455 F.2d at 185; United States v. Frascone, supra, 299 F.2d at 829.
Moreover, the evidence of appellants’ guilt, the sufficiency of which is not contested here, was overwhelming. Even exclusive of Saia’s testimony, evidence, much of it drawn from appellant Price’s own testimony, establishes appellants’ presence in Shelby on the day of the crime; their intention to commit a robbery; that large amounts of jewelry were seen in appellant Pellegrino’s apartment; and that appellants, with large sums paid in cash, purchased expensive cars shortly after their return from their southern escapades. Under the circumstances we cannot say that the interventions of the trial judge were such “plain error,” Fed.R.Crim.P. 52(b), as to require a new trial.
Appellants also argue that it was error for the trial court to refuse to order the sequestration of the FBI agent in charge of the case who sat at the prosecution table throughout the trial and was the last witness called by the Government. Since the chief investigating agent may be of significant help to the prosecution during the course of a trial, the trial court has discretion to make an exception to the general rule of sequestration of witnesses in his case. United States v. Wells, 437 F.2d 1144, 1146 (6th Cir. 1971); United States v. Frazier, 417 F.2d 1138, 1139 (4th Cir. 1969), cert. denied, 397 U.S. 1013, 90 S.Ct. 1245, 25 L.Ed.2d 427 (1970). No showing of prejudice flowing from the order of Government’s proof is made by appellants. Furthermore, before the agent began his testimony the court properly pointed out to the jury that the witness had heard all the previous evidence while seated at the counsel table. Under the circumstances the trial judge did not abuse his discretion in refusing sequestration and allowing the agent to testify at the end of the Government’s case.
Appellants next contend that the trial court erred in answering affirmatively without further inquiry a “legal question” posed by the jury as to whether the phrase “cause to be transported” could be substituted for the phrase “did transport” in the indictment *1209charging the appellants with violation of § 2314. Appellants apparently argue that an affirmative answer implied that appellants could be found guilty solely of aiding and abetting the § 2314 violation when they were not charged with aiding and abetting in the indictment and the only crime proved by the Government was the substantive violation. This argument ignores the fact that by virtue of 18 U.S.C. § 2(b),4 § 2314 incorporates the phrase “cause to be transported,” see Pereira v. United States, 347 U.S. 1, 8, 74 S.Ct. 358, 98 L.Ed. 435 (1954); thus the indictment in effect charged appellants with causing the stolen jewelry to be transported in interstate commerce. Furthermore, a defendant may be indicted for the commission of a substantive offense and convicted solely as an aider and abettor even though not named as such in the indictment. United States v. Tropiano, 418 F.2d 1069, 1083 (2d Cir. 1969), cert. denied sub nom., Grasso v. United States, 397 U.S. 1021, 90 S.Ct. 1258, 25 L.Ed.2d 530 (1970). Accord, United States v. Harvey, 439 F.2d 142, 143 (3rd Cir.), cert. denied, 403 U.S. 934, 91 S.Ct. 2264, 29 L.Ed.2d 713 (1971); United States v. Weisscredit Banca Commerciale E D'Investimenti, 325 F.Supp. 1384, 1395 (S.D.N.Y.1971). Additionally, there was substantial evidence from which the jury could have found that even if the crime were committed by Saia, as appellants contended at trial, appellants associated themselves with the venture, sought to make it successful and thus were guilty of aiding and abetting. United States v. Curiale, 414 F.2d 744, 748 (2d Cir.), cert. denied, 396 U.S. 959, 90 S.Ct. 433, 24 L.Ed.2d 424 (1969). Finally, appellants failed to object to the judge’s answer to the question posed by the jury and since the answer was not “plain error” they are precluded from raising the objection here. See Ramey v. United States, 118 U.S.App.D.C. 365, 336 F.2d 743, 744-745, cert. denied, 379 U.S. 840, 85 S.Ct. 79, 13 L.Ed.2d 47 (1964).
Lastly, appellants contend that their motion for a new trial based on newly discovered evidence was erroneously denied by the district court. It is well settled that appellate deference is given, however, to the denial of the motion by the judge who heard all the evidence during the trial. E.g., Connelly v. United States, 271 F.2d 333, 334 (8th Cir. 1959), cert. denied sub. nom., Caudle v. United States, 362 U.S. 936, 80 S.Ct. 755, 4 L.Ed.2d 750 (1960); United States v. Troche, 213 F.2d 401, 403 (2d Cir. 1954). The district court’s denial here was far from an abuse of discretion. One of the affidavits submitted with the motion for a new trial was merely cumulative. And the information in it could have been discovered by the exercise of due diligence on the part of appellants since they had ample contact with the affiant prior to trial. See United States v. Bradwell, 295 F.Supp. 958, 959-960 (D.Conn.) aff’d, 388 F.2d 619 (2d Cir.), cert. denied, 393 U.S. 867, 89 S.Ct. 152, 21 L.Ed.2d 135 (1968). The other affidavit, which contains an allegation that the witness Saia was lying, merely bears on Saia’s credibility; it does not, in and of itself, furnish adequate grounds to merit a new trial. United States v. Curry, 358 F.2d 904, 919 (2d Cir.), cert. denied, 385 U.S. 873, 87 S.Ct. 147, 17 L.Ed.2d 100 (1966).
Affirmed.