U.S. officials are not investigating the death of the Rev. Jim Jones, who was killed by a gunshot while almost 900 of his followers died of poisoning nine days ago in their Guyana commune.

It is not known whether Jones, leader of the ill-fated cult, committed suicide or was shot by one of those who later drank the fatal cyanide mixture or who fled the scene of the wholesale suicides.

"Jones' death is not under investigation. We see no violation of U.S. law in Jones' death." Justice Department spokesman John Russell said yesterday. He added that the department and the FBI are investigating only the fatal shooting of Rep. Leo J. Ryan (D-Calif.) under a section of the U.S. code making it a federal crime to kill a member of Congress. That statute has been interpreted as extending beyond U.S. borders.

Jones' body, one of 912 flown to Dover Aire Force Base in Delaware in a three-day airlift, will be cremated and the ashes - with those of his wife, Marceline, and their children - scattered over the ocean, a spokesman for Mrs. Jones' parents said yesterday in Richmond, Ind.

"I feel they have made a wise decision," funeral director Ernest Mills said by telephone yesterday. He said Jones' in-laws. Walter and Charlotteeee Baldwin of Richmond, "were very much influenced by what they feld was best for the community of Richmond and all concerned" in abandoning earlier plans for funeral services.

Mills said the Baldwins had returned from a visit to the South American colony of Jonestown three days before the Nov. 18 holocaust and found it "an ideal and happy settlement . . . Probably no one will ever know the truth as to what went wrong."

Jones' body remains in a refrigerated van at Dover, where FBI and military technicians are rushing to identify the victims before the bodies are too decomposed. They have fingerprinted and taken dental X-rays from more than 600, Air Force officials reported. Only 40 have been positively identified, including Jones, the only person officially confirmed as among the dead.

State and Justice Department officials said no autopsies will be done because there is no indication the deaths were in violation of U.S. law. Guyana officials autopsied a sample of the remains, but findings were not reported to the United States, State Department spokeswoman Kate Marshall said.

The Justice Department's Rusell said the FBI has "enough eyewitnesses who have given us accounts of what happened at Jonestown" and has no need of autopsy findings.

An airman who volunteered to help with the mortuary work at Dover was quoted describing the remains as "an unintelligible mess" He said they are undistinguishable by race of facial features, and that only morticians could determine the gender of the badly decayed bodies.

Thirty FBI agents maintained a visit at Charleston Air Force Base yesterday, waiting to interview about 80 survivors of the encampment who will be flown to South Carolina by military plane today or tomorrow. The agents are seeking possible conspirators in Ryan's murder.

U.S. Attorney Thomas Lydon, who is overseeing the operation, said investigators have found no evidence that "death squads" of Jones' loyalists are waiting to assassinate them, as many survivors fear.

Lydon said that although the Justice Department has no evidence of any potential attackers, "we are prepared to handle any death squads that may be lurking around."

In Los Angeles, it was reported yesterday that District Attorny John Van de Kamp received a letter in September signed by 653 Peoples Temple members, all now thought to be dead, begging him to cease his investigation of Jones' activities in that city.

The letter, accompanied by 12 pages of signatures, referred to Van de Kamp's probe into alleged coercive taking of property by Jones. The probe was initiated last May when an elderly Los Angeles couple, former cult members, complained they were forced to sell their home and rental property and give Jones the $125,000.

Van de Kamp said he has turned the letter over to the State Department to help in identifying the Jonestown dead.