Joseph Michael Payne, 32, was arrested in February for possessing child pornography and sexually assaulting a child. But before he went to jail, someone -- possibly him -- sent an email to the sheriff's department identifying him as Trang Michelle Van's killer.
Now, investigators believe she's not his only victim.
For 12 years, Payne dutifully clocked in and out at Andy Valero's auto service shop.
"He came to work everyday, went to lunch, came back to work. I mean, he's a hell of a technician," Valero said.
Valero thought he knew him, but maybe he didn't know him at all.
"It is very hard to believe a young man like him would do anything because of the fact that he worked with me side by side," he s aid.
Payne is now charged with killing Van on July 2, 2009. The prosecutor says Payne sent out red flags soon after Van's father found her stabbed to death inside their northwest Harris County home. But it wasn't until emails sent by clicking on the "Contact Us" tab on the Harris County Sheriff's Office website in January that investigators zeroed in on Payne.
"One of those emails was reportedly from an email address attributed to Joseph Payne. We were able to do some warrants and court orders to determine the source of the IP address and that indicated that it came from his home," Harris County Assistant District Attorney Katherine McDaniel said.
Detectives believe Payne happened upon his victim. She didn't know him, he knocked on the door and when she answered, forced his way in. When she wouldn't have sex with him, they say, he stabbed her. She crawled to a closet, where she died.
Payne, who's already charged with multiple counts of child porn and sex assault of a child, is being investigated for other murders near where he worked.
Valero says investigators have been interested in his time cards.
"I hope ain't none of that is true because if he did, he had us fooled for 12 years," Valero said.
It's believed that Van's murder happened sometime during his lunch hour back in July 2009.
Payne is now charged with capital murder and is being held without bond.
The prosecutor says he talked about the murder to people and he even posted an apology on Facebook, so detectives are still trying to determine if he was he looking to get caught or if he is, indeed, linked to more murders.