Aaron Hernandez's attorney claims there's reason for concern with one of the jurors who helped convict the former NFL star of first-degree murder. The attorney claims that the juror may have been "untruthful" throughout the jury selection process.

According to ESPN, Hernandez's attorney, James Sultan, also contendsthat an anonymous tipster called him on April 16. The incident reportedly happened a mere hours after the former New England Patriots tight end had been found guilty in the June 2013 execution-style killing Odin Lloyd in North Attleborought.

The attorneys claims were made public on Monday through redacted court documents.

Details from the conversation were not released in the court documents. The name of the caller was also not revealed. But Sultan later told a judge the female caller phoned several times and in one instance, claimed the juror in question was once present for a discussion she overheard about a double-murder in Boston that Hernandez has also been charged in connection with.

Mention of those killings was barred at the Lloyd trial, and Hernandez has pled not guilty to murder charges. Sultan also insists that the caller told him she overheard someone else say the juror specifically wanted to be seated in the Hernandez case.

"She told me she does not want [redacted] into trouble, but it is on her conscience that she knows some information which may be important," Sultan wrote.

He added that if the juror admitted having knowledge of the Boston case during jury selection, his defense team would have requested that the person be excused.

Sultan is now asking the judge to authorize a subpoena to trace all the related calls made to him, all of which he claims were made from a blocked number.

According to The Associated Press, jury selection in the Boston case is slated to start on Dec. 1, and an opening trial date has been set for Jan 4.

In that case, Hernandez, who has already been sentenced to life without parole stemming from the Lloyd conviction, is accused of opening fire on the two unsuspecting men after one of them accidentally spilled a drink on him in a nightclub and failed to apologize.