Former NFL wide receiver Sergio Brown pleaded not guilty on Wednesday to the murder of his mother.

Myrtle Brown was last seen alive in the early evening of Sept. 14 at her home. Two days later, after not hearing from his mother, one of her sons went to the home he shared with her and found blood on the back patio while no one was home, FOX 32 Chicago reported, citing court documents.

Brown was later found about 100 to 150 feet from her own back door. She was 73.

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Sergio Brown vs Colts

Jan 4, 2015; Indianapolis, IN, USA; Indianapolis Colts free safety Sergio Brown (38) against the Cincinnati Bengals during the 2014 AFC Wild Card playoff football game at Lucas Oil Stadium. (Andrew Weber-USA TODAY Sports)

Brown, 35, was taken into custody after trying to re-enter the United States into California from Mexico by the San Diego Police Department Threat Management Unit and several other local and federal agencies after a warrant for his arrest was issued in Illinois. 

The Cook County Medical Examiner’s Office ruled Brown's death a homicide, saying she was injured during an assault.

Brown was officially listed as missing in mid-September when his mother died. But, shortly afterward, he appeared to put out a video on an Instagram account named @intplayerwithapassport, even though he has a verified account on the platform already. In the video, the former defensive back called the death of his mother "fake news" and said "it has to be the FBI."

Sergio Brown with the Colts

Sergio Brown #38 of the Indianapolis Colts seen on the sidelines during action against the Jacksonville Jaguars at Lucas Oil Stadium on September 23, 2012 in Indianapolis, Indiana. (Michael Hickey/Getty Images)

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"Fake news. Fake news. Fake news," he said the video in which he tagged ESPN. "It has to be the FBI that came into my house on Bob Marley’s death day with the 511 haze and gas unwarranted. They kidnapped me twice from home — the Maywood Police Department. It had to be the FBI or the Maywood Police.

"I thought my f---ing mama was on vacation in Sinaloa. That’s f---ing fake news. Get the f--- out of my g------ face. She’s retired, and you want to come to me? The FBI had to do it. They have some power to do some s--- like that. What the f--- is going on? That’s fake news."

Shortly after her death, it appeared that Brown was seen partying in Mexico. He bought a one-way ticket to Cancun on Sept. 15.

Sergio Brown during an NFL game

Sergio Brown #38 of the Indianapolis Colts looks to the sidelines in the first quarter of a game against the Tennessee Titans at LP Field on December 28, 2014 in Nashville, Tennessee. The Colts defeated the Titans 27-10.  (Wesley Hitt/Getty Images)

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He was arrested on a first-degree murder charge in connection with the homicide

Brown played seven seasons in the NFL with the Patriots, Indianapolis Colts, Jacksonville Jaguars and Buffalo Bills. He last played in the league in 2016.

He's scheduled to appear in court next January.

Fox News' Paulina Dedaj and Ryan Gaydos contributed to this report.

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