EVERETT (AP) — Two people have been arrested in the fatal stabbing of a 50-year-old woman whose body was concealed beneath a mattress in a home south of Everett.

Snohomish County sheriff's detectives arrested a 59-year-old Marysville man on investigation of first-degree murder Tuesday.

They also arrested his former girlfriend, a 54-year-old woman who was also staying at the home, on investigation of rendering criminal assistance.

The Daily Herald says detectives believe the woman was killed May 25 after she confronted the man when visited his ex-girlfriend at the home.

According to court records released Wednesday, the ex-girlfriend told detectives that the male suspect attacked the victim from behind as she sat on a couch.

Court records show the victim's other roommate contacted police early Tuesday when he smelled a foul odor coming from her room and discovered her body in the bedroom.