SANTA ROSA, Calif., Nov. 14 — The death of an ex-Marine whose decapitated body was unearthed last week and whose wife was later found shot to death has led to murder complaints against six persons, two of them former disciples of Charles Manson.

The slayings of James T. Willett, 26, of Los Angeles and his wife, Lauren, 19, apparently were carried out to prevent Willett from telling police about robberies in the Los Angeles area, according to Sonoma County Dist. Atty. John Hawkes.

Hawkes said Monday that the Willetts and three men arrested in the case had shared a two-bedroom resort cabin at the Russian River town of Guerneville, until Willett was shot repeatedly and buried in a nearby redwood grove about Oct. 10.

“He was killed because the others were afraid he’d tell about robberies the three men committed in the Los Angeles area,” Hawkes said. “Apparently Willett was not involved in the robberies and his relationship with the men is unclear.”

Willett’s body, beheaded and dressed in a Marine’s blue tunic, was found last Wednesday after a hiker spotted a hand protruding from the ground. He had been shot with a .22-caliber pistol and 12-and 20-gauge shotguns near the burial site, Hawkes said.

Police found Mrs. Willett’s body beneath the house in a freshly dug hole Sunday after locating Willett’s station wagon parked outside. Investigators said she had been shot once in the forehead with a .38-caliber pistol, possibly last Friday.

A seven-month old baby girl was found inside the house unharmed and was believed by police to be the Willett’s child.

Three women and two men were arrested at the house and formally charged in Stockton Municipal Court with murder in Mrs. Willett’s death. All were held without bail, and the two men additionally were charged with being ex-felons in possession of firearms and illegal weapons.

The five were identified as Michael Lee Monfort, 24; James T. Craig, 33; Priscilla K. Cooper, 21, all of San Jose, Calif.; and Nancy Laura Pitman, 24, and Lynnette Alice Fromme, 24, both of Los Angeles.

The Sonoma County District attorney’s office later filed murder complaints in Willett’s death against Monfort, Craig and William Gaucher, about 25, arrested by Stockton police during the armed robbery of a liquor store.

Miss Fromme was a key defense witness at the trial in which cult leader Charles Manson was sentenced to death in the slayings of actress Sharon Tate and six other persons.

Miss Pitman was among a trio of females who maintained a vigil outside the Los Angeles courtroom during the lengthy trial.

Although not identified as a clan member, Miss Cooper had an “X” scar on her forehead like those Manson’s followers carved after he inflicted one on himself during the trial, police said.