DOVER, Del. (AP) -- The remains of all seven members of Columbia's crew have been positively identified, NASA officials said Thursday.

The identifications were made at the military mortuary at Dover Air Force Base, where the remains were taken after the space shuttle disintegrated Feb. 1.

"We are working toward releasing the crew remains to the families for their own private memorial services," said Eileen Hawley, a spokeswoman for the Johnson Space Center in Houston.

NASA officials provided few details, but said the death certificates were signed in Angelina County, Texas.

"We are comforted by the knowledge we have brought our seven friends home," Bob Cabana, director of Flight Crew Operations at the Johnson Space Center, said in a prepared statement. "We are deeply indebted to the communities and volunteers who made this homecoming possible, and brought peace of mind to the crew's families, and the entire NASA family."

Officials at the Dover Air Force Base had no comment and referred questions to NASA.

"It's totally their release authority," said base spokeswoman Lt. Olivia Nelson.

Officials said private memorial services for the crewmembers will take place within the next few weeks.