A juror during the murder trial of former NFL player Aaron Hernandez may have been "untruthful" during the proceedings, raising concern for the legal team of the convicted murderer.

Hernandez's lawyer James Sultan, according to ESPN, said in court documents released Monday that a female tipster first phoned him a day after the conviction. The counsel said the caller would not reveal her identity even if she called him several times using a blocked number.

In their conversations, the tipster said that the juror had been present during one of the discussions of Hernandez's double-murder trial in Boston, which was barred from any discussion during the Odin Lloyd trial.

The anonymous tipster also reportedly told Sultan that the juror really wanted to sit on Hernandez's panel.

"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," the lawyer wrote in the documents.

He furthered that if that particular member of the jury disclosed knowing about the case, the defense team would have the juror excused.

According to ESPN, a juror was dismissed during the trial when the judge found out that there was evidence that she had previously discussed the case. Now, Sultan is asking a subpoena to trace the calls made to him by the tipster.

CBS Boston said Superior Court Judge Susan Garsh partially unsealed the documents submitted by Sultan claiming that "a juror knew details of the case outside of what was presented in the courtroom." Garsh reportedly ruled that the juror's identity be protected.

Last month, Hernandez pleaded not guilty to the  witness intimidation charge of former pal Alexander Bradley.

The Washington Post  added that this was the same plea he entered for the double murder case he is also facing for allegedly killing Safiro Furtado and Daniel Abreu in 2012. Bradley was said to be Hernandez's companion when the two were killed in Boston. 

In April, the 25-year old Hernandez was sentenced to life without the possibility of parole, after a jury found him guilty of first degree murder for the 2013 death of Lloyd.

CNN has learned that he was also found guilty of illegal possession of a firearm and ammunition.

While he was being taken back to state prison from the courthouse, Hernandez denied that he was the murderer. "They got it wrong. I didn't do it," he was quoted as saying.

The future was bright for Hernandez until Lloyd's bullet-riddled body was found at an industrial park near the former NFL star's home in North Attleboro, Massachusetts, in June 2013.

According to Newsweek, the 6-foot-2 football player was selected in the fourth round of the 2010 NFL draft along with Rob Gronkowski, who was considered the league's best tight end. Hernandez only came next to him.

During the seasons they played together, the two reportedly caught 187 and 175 passes, respectively.