Prince George’s County police have arrested a Laurel man who they say stabbed and beat a couple to death while the woman’s severely disabled daughter watched. A love triangle, officials say, could be partly to blame.

Surveillance video and DNA evidence tie Thurston Lamont Yerby, 47, to the May double homicide, authorities say. Police say Yerby was romantically linked to Tina Lynn Towler, 45, who was killed in a Laurel apartment along with her live-in boyfriend, James Vell Ferguson, 42.

“At this point, the exact motive is unclear, but we think that the romantic relationship played some sort of involvement in those crimes,” said Julie Parker, a Prince George’s police spokeswoman.

Police arrested Yerby in the District after a traffic stop Thursday, Parker said. He was in custody of D.C. police and is scheduled to be taken Monday to Prince George’s, where he faces first-degree murder charges.

Detectives recovered multiple weapons from the scene, including household items and a knife, Parker said. She said Yerby’s DNA was found on items “that the suspect used to attempt to clean up the crime scene.”

Surveillance video also shows Yerby’s truck coming to and from the apartment complex at the time of Ferguson’s and Towler’s deaths, Parker said.

In an interview with police, Yerby said he knew Towler and Ferguson, but had never been inside their home, according to charging documents.

Homicide detectives identified Yerby as a suspect early in the investigation because of his relationship with Towler, authorities said.

Yerby’s family could not immediately be reached for comment.

Police said they have been unable to collect information about the homicide from Towler’s daughter, Jasmine “Jazzy” Gilbert, 26. Gilbert has cerebral palsy and cannot walk or talk.

Gilbert was in the room when her mother and her mother’s boyfriend were killed, but police do not know what Gilbert saw.

“It would be reasonable that she would have either witnessed the homicide or a portion thereof, but as we already articulated, there is a question of communicating with the victim’s daughter,” said Maj. Cesar Pacheco, commander of the police department’s criminal investigation division.

A nurse on a routine visit to care for Gilbert discovered Towler’s and Ferguson’s bodies the morning of May 2 in the one-bedroom apartment.

Gilbert is now under the care of the state of Maryland, Parker said. Dana Daniels, a close friend of Towler’s, said Gilbert has been placed in a group home.

Daniels said she does not know Yerby. Daniels said she is happy to see an arrest in the case, but still has questions about her friend’s death.

“You have somebody, but you want to know what was the reason,” Daniels said. “We just have to wait and see what happens.”