(CNN) -- A Texas death row inmate escaped from the Harris County Jail in Houston on Thursday, dressed in civilian clothes and carrying identification indicating he worked in the attorney general's office, a sheriff's department spokesman said.
Charles Victor Thompson, 35, was convicted of capital murder in April 1999 in the shooting deaths of his former girlfriend, Dannise Hayslip, and her friend, Darren Cain, 30.
The convict, who was re-sentenced to death Monday, slipped out of the jail around 3:30 p.m., wearing khaki pants, a dark blue shirt and white tennis shoes, according to sheriff's Lt. John Martin.(See video of the daring escape -- 1:28)
"He also had sort of a tag or an ID that indicated he was with the attorney general's office," Martin said.
He said he didn't know whether Thompson escaped on foot or in a vehicle.
"We definitely believe him to be dangerous," Martin told CNN Thursday night.
Thompson had been released from his cell block for a visit with his attorney in a private booth, where Plexiglas separates inmates from attorneys, Martin said.
The room is not monitored by authorities and no deputies are present in the room -- an effort to protect attorney-client privilege. Only a few sheets of paper could be slipped under the window, he said.
"He managed to change out of the orange jumpsuit that inmates commonly wear," Martin said. "The inmate jumpsuit was found in the attorney booth."
It was not immediately clear whether Thompson had had an attorney visit him on Thursday, or whether he had merely gone to the area on the pretense of seeing his lawyer.
Thompson went from the attorney booth to the floor's control center, where he told a deputy that he was conducting an investigation with the attorney general's office, Martin said.
"He was convincing enough that he was able to convince one of our deputies to let him out of the facility," he said.
When did authorities realize a death row inmate had simply walked out their doors?
"We realized it almost immediately," he said. "This was obviously something that was pre-planned."
The new sentencing hearing was ordered by the Texas Court of Criminal Appeals, which had upheld Thompson's conviction.
Martin said Thompson was brought to the county jail in May, and it was unclear when he would have been returned to the Department of Corrections and death row.
The Gulf Coast Violent Offenders Task Force was aiding the search.
Martin said it had been several years since anyone escaped from the jail.
"This is extremely rare, especially for someone who has been sentenced to death on a capital murder charge."