Investigators still are perplexed about what led to Khaya Lambert's killing. It is a mystery that has plagued the officers -- and the city -- since the grisly murder scene was discovered on June 21, 2017.

Baltimore police were actually called to the scene in Liberty Heights because suspect William Mason, 32, was reported to have a knife and was trying to attack a neighbor. The neighbor wasn't injured.

"The victim reports that he was laying in his apartment when he heard a loud crash coming from his kitchen area. He went to check to see what the crash was, he found the suspect laying on his kitchen floor covered in blood," Baltimore police Detective Donny Moses told WBALTV.

Not only was Mason covered in blood, but he was reportedly naked as well. Police grew suspicious as they checked out the scene. Something just wasn't right.

"They noticed blood prints on the inside of the apartment, outside of the apartment, in the hallway of the apartment. Of course, they were curious. They follow the prints to another apartment inside of the building where they located an open door," Moses told the TV station.

And that's when they found Lambert. "The victim in this case, and the male who we had just arrested, Mr. Mason, were actually live-in boyfriend and girlfriend, and they had some sort of domestic incident, which resulted in our victim's murder," Moses was quoted as saying.

The couple evidently got into a "heated encounter," Moses told the Baltimore Sun. A GoFundMe set up to help Lambert's family has gotten more than $3,500 of its $5,000 goal.

Mason is charged with first-degree murder in the slaying.