Police responded to a disturbance call at 15 Paseo Luna at about 11 p.m. There were two women arguing, and one wanted to get into the condo to get personal belongings, deputies said.
"She wanted deputies to go in with her to keep the peace," said Jim Amormino from the Orange County Sheriff's Department.
However, deputies encountered Needham, who was naked, uncooperative and combative, Amormino said. Police used a Taser to take him into custody for questioning.
Police went into the condo and found the body of a badly beaten 19-year-old woman. She was transported to a local hospital, where she was pronounced dead about an hour later of traumatic injuries.
The suspect's brother Matt Needham said the suspect hasn't been the same since returning from his second tour of Iraq.
"He's been no good since he got back, i'll be honest. I mean, he's my brother, we grew up in the crib together, I love him like no one else, and it's sad to know the person who means the most to me, to completely write them off because they're crazy, you know," he said.
Matt Needham said the family had been encouraging the brother to break up with him girlfriend.
"No one figures a bad breakup is like this. Everyone figures you yell at each other and you fight or whatever," Matt Needham said. "I never saw this coming, but I'll tell you what, with my brother, you know, the mental state since Iraq, nothing would surprise me."