CNN– Former NFL player Sergio Brown is missing after his mother died from injuries related to an assault and her body was found near a creek behind her suburban Chicago home, according to police and records obtained by a CNN affiliate.

Authorities discovered the body of 73-year-old Myrtle Brown on Saturday after relatives alerted police they’d been unable to find or contact her or her son, the Maywood Police Department said in a news release.

The Cook County Medical Examiner’s Office determined Myrtle Brown died from injuries related to an assault, and the manner of death was ruled a homicide, records obtained by CNN affiliate WBBM show.

Sergio Brown’s brother on Sunday took to social media to ask for help in finding him.

“My brother Sergio is still missing,” Nick Brown wrote on Instagram. “If anyone knows where he is I want him to know that I love you and please come home.”

Police tape cordoned off a residential street in Maywood – about 15 miles west of the Loop – as police responded, video from WBBM shows.

“Myrtle, she was an outstanding woman, and I’m hoping she’s in the right place and she’s with God,” Carlos Cortez, Myrtle Brown’s next-door neighbor, told WBBM. “I never would’ve expected this in a million years.”

Sergio Brown, 35, played for Notre Dame before signing with the New England Patriots as an undrafted free agent in 2010. He played seven seasons in the NFL as a member of the Patriots, Indianapolis Colts, Jacksonville Jaguars and Buffalo Bills.

“It’s a sad but hopeful time, and we will all get through this together,” Nick Brown wrote online. “Mom always told me, ‘tough times don’t last’ and our last conversation about tough times being temporary is my beacon of hope.

“Mom, thank you for being strong, caring, diligent, fancy, funny, and for saving my art. I won’t let you down.”

The investigation continues, according to Nick Brown, who asked people not to approach the family’s property and contact Maywood police with any information about his brother’s whereabouts.

Anyone with information can contact an anonymous tip line at 708-450-1787, police said. The lead investigator on the case, Dennis Diaz, did not respond to CNN’s request for more information. CNN has reached out to Brown family members.

CNN’s Alisha Ebrahimji and Caroll Alvarado contributed to this report.