HOUSTON -- A man confessed to killing a man during a robbery as well as several other violent crimes, officials told KPRC Local 2 Thursday. And police believe there are more victims who have been too afraid to come forward.

Houston police said Angel Gabriel Ramos, 29, shot Prisiliano Arizmendez, 47, during a robbery in a parking lot in the 8800 block of Hammerly Boulevard on Feb. 17.

Detectives said Ramos approached Arizmendez and demanded his wallet. Melesio Espino saw the robbery and fought with Ramos, police said. The men were shot and transported to a hospital in critical condition.

Arizmendez died three days later. Police said Ramos fired at least eight rounds during the crime.

Investigators noticed similarities with several other robberies and determined Ramos may have been responsible for them.

In most cases, Ramos approached victims in parking lots and demanded money, police said. The victims normally complied with Ramos' demands and, without any provocation, Ramos would shoot them, officials said.

Ramos was arrested at a motel in the 12100 block of the Northwest Freeway on March 22. Detectives said Ramos had a loaded .40-caliber pistol with 77 live rounds. Officers also found a 1991 Toyota 4Runner that had been reported stolen and was allegedly used in several robberies. Jewelry and other valuables, including a rare Vietnamese coin collection, were also confiscated.

Detectives said Ramos was arrested for his alleged involvement in an aggravated robbery in the 8500 block of Pitner Road on March 3. Alfredo Salvador, 24, suffered a gunshot wound to the face.

Investigators said Ramos confessed to Arizmendez's killing, five aggravated robberies, two automobile thefts and 10 burglaries.

Ramos told authorities he committed the crimes to support a crack addiction.

"He mentioned that it was near $1,000-a-day cocaine habit," said Art Mejia with the Houston Police Department.

Ramos may be involved in additional crimes, police said. Anyone who believes they may have information on additional crimes is asked to contact the Houston Police Department Robbery Division Latino Squad at 713-308-0700.