(AP) - Four Marines, including one known as"Psycho," told investigators they robbed and murdered a fellowMarine and his wife last month after breaking into their home insearch of valuables and sexually assaulting the woman, according tocourt documents.

The four were charged Wednesday with the execution-styleslayings of Sgt. Jan Pietrzak, 24, and Quiana Jenkins-Pietrzak, 26,who were found gagged, tied and shot in the head on Oct. 15 in theliving room of their home in Winchester, in Riverside Countysoutheast of Los Angeles.

The home was ransacked and jewelry and other items were taken,investigators said. A fire was set, apparently in an effort todestroy evidence.

Two of the accused worked for Pietrzak, who was a helicopterairframe mechanic at Miramar Marine Corps Air Station in San Diego.

Pietrzak, who was born in Poland and raised in Brooklyn,joined the Marines in 2003 and served in Iraq from July 2005 toFebruary 2006.

His mother, Henryka Pietrzak-Varga, told The Daily News on Wednesday that she had prepared herself for the possibilityof her son dying in Iraq.

"But to die like this, in their own home?" she said. "Theywere good kids. They didn't deserve to die like this."

Murder charges were filed against Lance Cpl. Emrys John, 18, ofMaryland; Lance Cpl. Tyrone Miller, 20, of North Carolina; Pvt.Kevin Cox, 20, of Tennessee, and Lance Cpl. Kesaun Sykes, 21, ofCalifornia. They do not have attorneys yet.

John and Miller worked for Pietrzak. Miller said he forced hisway into the home by pointing a shotgun at Pietrzak, according toan affidavit from a sheriff's investigator.

Miller said he and others went to Pietrzak's home to rob him,then tied up the couple and discussed with John whether to killthem.

Cox and Sykes, known as "Psycho," acknowledged they went tothe home to rob Pietrzak. All four said his wife was sexuallyassaulted, the affidavit said.

The document also said that shoes found at the barracks whereCox and John lived matched prints at the crime scene, and thatitems believed stolen from the house were found at Sykes' home.

The men were each charged with two counts of first-degree murderand special-circumstance allegations of committing multiplemurders, committing the crime during a robbery, and rape byinstrument, district attorney's spokesman Ryan Hightower saidThursday.

John, who prosecutors believe shot the couple, also was chargedwith a special-circumstance allegation of using a firearm toinflict great bodily injury or death.

Sykes, who lives in the Fallbrook area in San Diego County, wasarrested on Sunday. The other three Marines lived at the CampPendleton base and were held there until they were transferred to aRiverside County jail on Wednesday.

All were being held without bail Thursday. Their arraignment waspostponed until Nov. 20. Prosecutors had not decided whether toseek the death penalty.

"Marines are supposed to be brothers," Pietrzak's mother toldThe Riverside Press-Enterprise this week. "What kind of brothersare these?"