SOMERVILLE (CBS) — Middlesex County District Attorney Marian Ryan has identified the man found dead Tuesday night in the Mystic River as a suspect in the February murder of a Malden woman.

Kenneth Manning, 35, of Malden, was the lead suspect in the murder of Colleen Russell, 36, of Malden.

READ MORE: UMass Lowell Closed Tuesday Due To 'Possible Cybersecurity Incident'

Russell was found dead in an apartment around 9 p.m. February 15 after a well-being check was requested by family members. Officers found signs of a struggle inside Russell’s apartment and say she was killed by “sharp force injuries.”

Colleen Russell (WBZ-TV)

Colleen Russell (WBZ-TV)

Last week, Russell’s mother made a desperate plea for help from the public in catching her daughter’s killer.

“I cry every day over her,” Lucille Russell says. “I go to bed at night and sometimes the phone will ring and I forget for a second and I think it’s her.”

She said when her daughter brought home Manning, her new boyfriend, “we just knew that something wasn’t quite right.” She said she watched as Manning verbally abused her once vibrant, happy child.

READ MORE: Massachusetts Announces $1M 'VaxMillions' COVID Vaccine Lottery; 'If You're Not Vaccinated, You Can't Play'

“She became a shell of a person. The Colleen that we knew was gone a long time ago. He took that Colleen away from us.”

Manning, who was seen on surveillance leaving Russell’s apartment, allegedly stole Russell’s car after the murder. The car was found in Somerville on February 17.

Manning’s body was spotted by a passerby around 6:30 p.m. Tuesday in the river near the intersection of Shore Drive and Ten Hills Road in Somerville. DA Ryan’s office said the body appeared to have been in the water for an extended period of time.

Manning was last seen on February 16 in Somerville; an arrest warrant for Manning was issued February 18.

MORE NEWS: Fourth Stimulus Check: Will You Get Another Relief Payment?