That argument seemed to have gained a foothold in jurors’ minds.

“He couldn’t remember half the things he said the week before,” Joseph Roldan, a juror, said of Mr. Rechnitz in an interview after court. Mr. Rechnitz had appeared to be “in it for himself.”

Jurors who had trouble stomaching the content of Mr. Rechnitz’s testimony may also have taken issue with the length of it: His time on the witness stand took up more than half of the days of testimony during the trial, which began on Oct. 23.

The judge, Andrew L. Carter Jr. of Federal District Court in Manhattan, declared the mistrial on the sixth day of deliberations, after jurors sent a note telling him they could not reach an agreement, their second such note in three days. After the first note, on Tuesday, Judge Carter directed them to continue deliberating.

The second note, which arrived around 2 p.m. on Thursday, said the jurors saw “no prospect of making further progress,” despite “continued, spirited discussion and contemplation of the evidence.”

Defense lawyers moved for a mistrial; prosecutors did not object.

Mr. Seabrook and Mr. Huberfeld, both 57, were each charged with one count of honest services wire fraud and one count of conspiracy to commit honest services wire fraud. Mr. Roldan said the jury had been leaning toward a split verdict, with a majority voting to find the defendants not guilty on the first count and guilty on the second. Eventually, they deadlocked with 10 jurors voting to find the defendants guilty on the conspiracy charge and two voting to acquit, and 11 jurors voting not guilty on the fraud charge and one voting to convict, he said.