QUARTZ HILL, CA -- Police announced Sunday that two men, one of them previously wanted by cops as a "person of interest", have been taken into custody in connection with the quadruple murders last week of a NASA engineer and three other people in his Quartz Hill home.

Jae Hwan Shim, 39, and another man who has not been identified, were taken into custody Saturday about 9 p.m. in Douglas, Arizona, a border town 90 miles southeast of Tucson.

Shim's vehicle, a 1998 Mercedes-Benz E-320 with a California license number of 4ANZ159 is still missing, said Deputy Oscar Butao.

Another person of interest, Si Young Yoon, 34, has not been found.

Yoon's vehicle has been located in Parmdale, Butao said.

Yoon and Shim were last seen leaving their homes Monday, the same day a fire occurred at 43250 N. 45th Street West in Quartz Hill that was quickly labeled suspicious by authorities.

The victims' remains were found after firefighters put out the flames about 5 p.m. Monday.

They were not killed by the fire, according to the coroner's office.

Joseph Paul Ciganek, a 60-year-old NASA engineer who worked at the Dryden Flight Research Center on the Edwards Air Force base, is the only victim to be publicly identified.

Ciganek's body was found in a different room than the other victims - a woman, a boy and a girl who shared a different surname, said Assistant Coroner Chief Ed Winter.

Ciganek and the boy had been "beaten and slashed" and both died from blunt force and sharp force trauma, Winter said. The woman and girl suffered multiple stab wounds, he added.

The Los Angeles Times reported that Ciganek was killed soon after he came home from work and that his wife, Jocelyn, was on her way home from her job at a nearby mall when the fire broke out.

The dead woman and children were relatives of Jocelyn Ciganek who had been living in the home with the couple, Los Angeles County Sheriff's Lt. David Coleman told The Times.

Friends and relatives told The Times they were Jenny Park and her children Jamie, 13, and Justin, who was 8 or 9. Jae Hwan Shim was reportedly once briefly married to Park and a stepfather to her children.