HOUSTON – A man, initially charged with murder, accused of stabbing a 14-year-old boy to death in June is now charged with capital murder, officials said.

Additional information that was not available when the charge was initially filed led to an upgrade in charges, Assistant District Attorney Denise Nichols said. After questioning other minors who were in the vehicle at the time of the incident, investigators learned that Joseph Aguirre Flores was murdered during the course of a robbery, which constitutes a capital murder charge, authorities said.

Disturbing details in Flores' death were released Saturday.

Police found Flores on June 20, bleeding in the street at 9800 Beechnut St. He was taken to a hospital, where he underwent surgery, but died.

Police received a Crime Stoppers tip on June 21, that led to the arrest of Christopher Bert Taylor, 52. Taylor is charged with capital murder.

According to court documents, a witness told police she and Taylor were panhandling at Beechnut and the Beltway when Flores pulled up in a silver van. The witness said Flores invited both of them into the van.

The witness said Taylor got into the front seat and she got in the back. She also noticed another person wearing a mask was sitting in the cargo area of the van.

The witness said an argument broke out after Flores stopped the van in a parking lot. She said Flores and the other passenger threatened to kill Taylor, but a weapon was never seen or mentioned.

She said when Flores tried to move to the back seat of the van, Taylor pulled a pocket knife from his back pocket and stabbed Flores about seven times. She then said Taylor demanded money from Flores during the stabbing.

"The state alleges that after speaking to the surviving male in the vehicle, that during a conversation, in the vehicle, the defendant pulled out a knife and stabbed the complainant multiple times," Nichols said. "According to that male, before the murder he had indicated to the complainant that he wanted his money and that this was a robbery."

The witness said she told Taylor to stop, and that Flores was also begging him to stop.

She said Flores was able to get out of the van and run, leaving the other occupant in the vehicle with the witness and Taylor.

The witness said the other passenger was still in the back of the van and Taylor was attempting to reach over the seats to stab him, too.

She said she got out of the van, opened the back door and told him to leave.

The witness then said she and Taylor ran around a building so no one would see them.

According to the witness, Taylor said, "I jugged him. I jugged him. I got him. I did it for you."

The witness told police she never felt threatened in the van because Flores and the other passenger were kids. She said Taylor should not have felt threatened because he could have gotten out of the van at any time. She said Taylor told her not to say anything about the crime so they would not get caught.

Police said Taylor admitted during a voluntary interview that he stabbed Flores at least twice.

Taylor told police that Flores got out of the vehicle when he tried to get in the back seat with the witness. When Flores attempted to get back in the van, Taylor said he started stabbing him because he was not sure what he was about to do.

According to court documents, Taylor told police he never saw a weapon of any type while he was in the van.

Police also spoke to the other juvenile. He said he was in the back of the van when Flores picked up Taylor and the witness.

According to court documents, the juvenile said Taylor pulled a knife and demanded their money. He also said Flores kicked the knife away from Taylor and tried to get out of the vehicle, but Taylor got the knife back and started to stab him.

The juvenile told police that, at one point, Taylor pointed the knife at him and told him to give him his money.

Court documents said the juvenile was able to escape from the van when the witness opened the back door.