CLAREMORE, Oklahoma - Claremore Police arrested a third suspect today for the murder of Dakota Rex.

Rex was shot during a home invasion robbery.

They were after marijuana according to police and it took a couple of months to track down tips and cell phone records that led to the three men.

Police said Dairon Brown didn't have much to say after this arrest, but he apologized. 

"I'm sorry to everybody that's involved in this," Brown said. 

He's the third suspect in Claremore's only murder this year - the shooting death of 22-year-old Dakota Rex.

It happened at 2:40 a.m. on May 16.

Three men went into a house and held several people at gunpoint.

"The robbers came to steal marijuana and money associated with the trade and Dakota Rex ended up losing his life when he got in a tussle with one of the suspects," said Claremore Police Deputy Chief Steve Cox. 

Police said it was Marquise White who fired the single, fatal shot. They found the bullet on the floor inside the house.

He was the second man arrested, along with Brown and Kairee Javon Cooks.

All three are from Tulsa.

"Our investigators have been working tirelessly," Cox said. 

Police said the case started with a few, critical leads. 

Through interviews and tips, detectives got the name "KJ Cooks."

Police got cell phone records that confirmed Cooks was near the scene.

Surveillance cameras picked up a car leaving the murder scene, and police determined Cooks had a matching car.

Police later got a recording of Cooks admitting he was in on the robbery.

They said once arrested, he identified the other two suspects.

Police said while the robbery was over drugs Rex was a completely innocent victim.

"Through everything we have learned, we believe he was trying to push them out the door to try and protect his friends and he was shot and killed," Cox said.