For more than two years, detectives searched for Vanessa Pham’s killer. The alleged murderer was tracking them, too, according to a search warrant.

According to the warrant, Julio Miguel Blanco-Garcia told investigators he monitored the probe into the high-profile slaying of the college freshman from Falls Church using the Internet, tracking new information as it was reported by the media.

The warrant, filed in Fairfax County on Wednesday, detailed for the first time what the 27-year-old Blanco-Garcia told police after his mid-December arrest, where he got the alleged murder weapon and what he allegedly took from the 19-year-old Pham during the 2010 killing.

His ex-wife also spoke about Blanco-Garcia on Thursday during a short interview, becoming his first close associate to discuss him publicly.

Matarida Hoesin said Blanco-Garcia sometimes smoked crack and could grow violent when he did so. On one occasion, she said, he pushed her down; another time, he held a knife to her face.

Vanessa Pham was found dead in her car in June 2010. A search warrent reveals new details about her alleged killer, Julio Miguel Blanco-Garcia. (PROVIDED BY THE PHAM FAMILY)

“He completely changed when he used drugs,” Hoesin said.

Pham was found dead in her white Scion hatchback on a Sunday afternoon in June 2010. Her car was spotted in a ditch on Arlington Boulevard in the Fairfax area. She had been stabbed multiple times in the upper body.

Surveillance video from a nearby shopping center showed the Scion leaving a parking lot minutes before Pham was found dead. The video showed no obvious signs of trouble.

Fairfax County police mounted an investigation but had little to show before Dec. 10. That’s when forensics experts told investigators that fingerprints taken from the scene of Pham’s killing matched those collected from a defendant who had recently been convicted of another crime in Fairfax County.

Three days later, Blanco-Garcia was picked up at a construction site in Vienna, where he was working. Immigration officials said he was a Guatemalan national in the United States illegally. Court records showed that he had a recent shoplifting conviction.

Following the arrest, Blanco-Garcia told detectives that the kitchen knife used in the killing was taken from his residence, according to the search warrant. He also told them he took Pham’s cellphone during the slaying and discarded it in a culvert. Police searched for the phone, but it was never recovered.

Police filed the search warrant because they wanted to search his residence for additional evidence.

The search warrant did not shed light on the case’s central question: Why would Blanco-Garcia kill Pham? Police have previously said they do not think that the two knew each other.

Hoesin, the ex-wife, said she met Blanco-Garcia in 2004. She was working at a Tysons Corner McDonald’s, she said, and Blanco-Garcia was her manager. She called him “friendly,” and they were both immigrants. She is from Indonesia.

They were married in Fairfax County the next year, but the relationship gradually unraveled. Hoesin said Blanco-Garcia was unfaithful and they clashed over cultural and religious issues. She said she is a Muslim and his family is Christian.

“There were too many issues between us that became unbearable,” Hoesin said.

The pair separated in 2008, and Hoesin filed for divorce the next year. They had no children. She said she never talked to him again after the divorce was filed, though he repeatedly called her.

“I don’t want anything to do with him,” she said.

David Bernhard, Blanco-Garcia’s attorney, declined to comment.