Oscar Alvarado, 27, escaped from the Curran-Fromhold Correctional Facility on State Road in the Northeast sometime between 3 and 6 p.m. Thursday, Commissioner Louis Giorla said.

"What we know right now is that he was able to exit his housing area and make way to the visiting area with an unauthorized pass, and that from that area he somehow exited the building," Giorla said at a news conference.

He said it was the first escape from the prison since it opened in 1995.

Alvarado, of Philip Street near Ontario in North Philadelphia, had been locked up on murder charges last year following an apparent robbery-turned-fatal shooting in North Philadelphia.

His grandmother Miriam Maldonado said yesterday that she didn't know where her grandson was. "He hasn't called me," she said in a telephone interview.

The city prisons allow visitors to see inmates on three holidays - Thanksgiving, Christmas and New Year's Day. This Thanksgiving was crowded as usual, but no one had signed in to see Alvarado on Thursday, Giorla said.

Normally after a visitor signs in, Giorla said, an inmate obtains a paper pass from a correctional officer in his housing unit to go to the visiting area.

Giorla said officials were interviewing correctional officers in Alvarado's housing unit, but he would not reveal what any of them said.

He said Alvarado is believed to have planned his escape for about 10 days, but he would not elaborate.

Giorla said that Alvarado was last observed in the visiting area about 3 p.m., wearing black trousers and a white or tan T-shirt. Alvarado had at some point changed from his two-piece, blue prison uniform. Giorla would not say who last saw Alvarado.

Alvarado was reported missing from his housing unit during the 6 p.m. check. He shared his second-floor cell with another inmate.

Prison officials said Alvarado's housing unit and the path he would have walked to go to the visiting area - which includes going through two sets of controlled double doors - are not equipped with video cameras. Neither are the visiting room nor the room where inmates are searched, for privacy reasons.

When asked if prison officials would consider equipping such areas with video cameras, Giorla said: "We're looking at all our procedures. . . . We'll evaluate it, and if we believe we have to make physical improvements, staffing changes or whatever actions we have to take, we'll take."

It was not clear yesterday if Alvarado had an accomplice, or whether he left in a vehicle.

Police spokesman Lt. Frank Vanore yesterday described Alvarado as a "dangerous individual."

Police said Alvarado is 5 feet 7, 160 pounds, with brown eyes. He is now believed to be clean-shaven, with a bald head or a close-cropped haircut.

He has a tattoo on his left upper arm that says "215 BADLANDZ" and another on his left forearm that reads "NEVA FALL IN LUV WIT LIFE CUZ U HAVE A PROMISE WIT DEATH."

Anyone with information on his whereabouts is asked to contact the Northeast Detective Division at 215-686-3153 or to call 9-1-1.

Alvarado is accused of fatally shooting Marta Martinez-Lozada, 37, during an apparent robbery on Oct. 21, 2008, on Lawrence Street near Lehigh Avenue in the Fairhill section of North Philadelphia.

Police spokesman Sgt. Ray Evers said yesterday that at 4:23 p.m. that day, police officers found Martinez-Lozada, of Hope Street near Cambria in Fairhill, suffering from multiple gunshot wounds. She was pronounced dead about 20 minutes later at Temple University Hospital.

Witnesses said the shooting had been committed by a Hispanic man in a red Honda Civic driven by a Hispanic woman, Evers said.

Police arrested Alvarado that day inside a house on Thompson Street near Hope.

Cynthia Alvarado, now 28, of Thompson Street near Hope, believed to have been the driver of the Civic, also was arrested that day. She also has been charged with murder, robbery and related offenses and is in custody at Riverside Correctional Facility on State Road.

Police have said that the Alvarados are cousins.

Oscar Alvarado faces another open court case. He was charged with aggravated assault, robbery and related offenses following an incident Oct. 18, 2008. About 2:50 a.m. that day, a 20-year-old woman on J Street near Luzerne was pushed by two Hispanic men who had exited a red car, possibly a Honda, Evers said.

One of the men, whom the woman later identified as Alvarado, had a black object in his hand, believed to be a handgun, Evers said. Alvarado allegedly demanded money from her, and told her that if she didn't comply, "I'm going to blow your f---ing brains out," according to a police report.

Evers said Alvarado struck the woman with his fist after stealing her handbag, before fleeing.

Three days later, Alvarado allegedly shot and killed Martinez-Lozada.