MAYWOOD, Ill. — The search continues on Monday for a missing former NFL player whose mother was found dead in a creek in the western suburbs over the weekend.

Authorities say they are searching for 35-year-old Sergio Brown, a Proviso East graduate who played in the NFL from 2010 to 2016 with the New England Patriots and Indianapolis Colts.

Sergio was reported missing alongside his mother, Myrtle Brown, hours before she was found dead.

A new post appeared on an Instagram account that is believed to be run by Sergio on Monday. In the post, which was shared as a story, Brown makes vague statements regarding the FBI and Maywood police and claims that he thought his mother was on vacation.

The Cook County Medical Examiner’s Office reports that Myrtle Brown died in an assault, and a homicide investigation into her death is underway.

“You just feel for the family, what they’re going through,” Angel Rivera, a neighbor who lives across the street from the Brown family, said.

Rivera says he was shocked to find out about Myrtle Brown’s death, and the shock only grew as the day went on.

“Saturday morning, when my wife told me Myrtle was missing, I was floored,” Rivera said. “We saw the commotion and realized that they had found the body and there were police everywhere.”

Myrtle’s sister, Sheila Simmons, spoke with WGN TV News on Saturday, hours after she got a call that both Myrtle and Sergio were missing.

“It’s devastating,” Simmons said. “I walked around the house and I saw things that looked out of the ordinary.”

Simmons said she didn’t find anything after searching the creek behind Myrtle’s house, but later in the day, she and other family members went back to search and discovered Myrtle’s body.

“Later on we got a group together and that’s when we found my sister in the creek, dead,” Simmons said.

The Brown family says police are reviewing video footage from around the house as part of their investigation.

“My sister is gone, that’s all I can say, I don’t know what happened,” Simmons said.

Police have not named Sergio Brown as a person of interest, but are asking anyone with information on his whereabouts to come forward.