He chose South and Central American women that were in the country illegally. After Farrow was finished taking pictures of them and they left, Timothy called them back to the studio, presumably under the ruse that Farrow had more work for them. He then bashed them over the head and killed them.
Brand's final victim was Estrella Carazo. Her hand was found after a man killed and cut open an alligator. Evidence showed that she had been murdered before her body was discarded in the Everglades.
Initially, the murder was believed by many including Dexter to have been committed by his associate, Jonathan Farrow, an S&M photographer. It was only after Dexter killed Farrow that Brand was arrested by Sergeant Angel Batista on solid surveillance and DNA evidence. This disturbed Dexter because he had broken The Code.
Because of Farrow's sudden disappearance, it was believed by everybody except Dexter that Brand had killed Farrow. Timothy was not seen again in the series after his arrest.