A Washington state man is behind bars after he allegedly killed his girlfriend, then chopped up her body and left her remains in an apartment.

Willie James McCoo, 55, stands accused of murder in the stabbing death of 31-year-old Kiara Sewell. Seattle police officers responded around 12:20 p.m. on June 15 to an apartment building in the 900 block of North 143 Street. When officers arrived, they located the alleged victim and immediately saw that Sewell had “obvious signs of trauma.”

According to a police report obtained by local NBC affiliate KING, McCoo and Sewell were seen on surveillance video going in and out of the building on June 8 and 9, but only McCoo was seen after that, the report said. He was often seen on video carrying duffle bags and garbage bags in the days before authorities discovered Sewell”s body, police said. A coroner determined Sewell likely died on June 10.

Love true crime? Sign up for our newsletter, The Law&Crime Docket, to get the latest real-life crime stories delivered right to your inbox

Detectives executed a search warrant on McCoo’s storage locker and reportedly discovered a machete with an 18-inch blade and a hunting knife with an 11-inch blade.

“What in the world did she do that you could have done something like this?” Sewell’s mother, Taneika Tigner, told local ABC affiliate KOMO. “I want him to pay for what he did to my daughter; he needs to rot. He stabbed her in the face. The back of her neck is decapitated.”

Cops arrested McCoo for murder on Monday. He’s in the King County Correctional Facility on a $4 million bond.

KOMO reported McCoo was released from prison last fall after serving nearly 20 years for attacking a woman with a knife while she was sleeping. He was convicted of first-degree assault and sentenced to more than 28 years in prison. But McCoo had about eight years taken off his sentence after the Washington Supreme Court ruled the state’s drug possession law was unconstitutional. McCoo had nearly 10 drug possession convictions that were factored into his sentencing guideline score. With those drug possession cases tossed, McCoo was resentenced to about 20 years.

More from Law&Crime: ‘Visibly apprehensive’: Boyfriend plunged knife into girlfriend’s back 5 times and left her to die at lake after confronting her about ex on video, police say

Sewell’s uncle Sekou Forrester told KING that the family feels the justice system let them down.

“He’s lived on this earth for this long and hasn’t done anything but cause destruction,” he said.

Sewell leaves behind her four children.

“Kiara wouldn’t want her friends and family and all that knew her to sit in sadness, yes mourn but don’t stay there but get up and move on and celebrate her life,” a GoFundMe post said. “When you think of her think about her beautiful smile, her wild and crazy stories, and her (off key) singing.”