TULSA, Oklahoma - Tulsa homicide detectives are working overtime to find who killed a man, his mother and her boyfriend on Monday.

Police believe the son was the target and the other two were killed because they were witnesses.

Police said they found Thomas Brown, Junior, shot to death right inside of the front door of a home located in the 200 block of East 29th Street North.

They believe his mother, Cara Brown, likely heard the commotion and got up. She was found in the doorway of her bedroom and her boyfriend was found dead right next to the bed - both of them shot to death as well.

Brown says on Facebook he attended Tulsa's Central High School and is now self-employed and started a relationship just a couple of weeks ago.

His mother's page has few pictures and no personal information.

Neighbors told police they heard yelling, screaming and shots, but didn't see anyone or a vehicle.

Police always start a homicide investigation by looking at the victims' lives.

They believe Brown was the focus of the crime.

Records show he has several arrests for drugs. He was convicted most recently in 2015, sentenced to four years in prison and released last June.

Detectives believe Brown knew the suspects because it doesn't look like they forced their way inside.

Sergeant Dave Walker said, “The house did not look like a fight for life, that's the first thing I noticed. The next thing is the suspects were looking for something. Drawers were opened and clothes were gone through."

Police believe they found what they were looking for then left.

"It's most likely going to be drugs, drugs or money. What are you going to kill that much for,” Walker said.

Detectives don't believe Cara Brown and her boyfriend were the original targets, but were killed because they were witnesses.

Walker said, "Once you kill the one, you gotta kill the other ones, looks like that's what happened."

Police want you to come forward if you saw a vehicle in the area around 2 a.m. or if you have direct knowledge of what happened.