The FBI has transcripts of at least some of the radio messages sent between Jonestown and the Peoples Temple headquarters in Georgetown during the hours immediately preceding the mass suicide-murder that left more than 900 of the late Rev. Jim Jones' foolowers dead Nov. 18.

The transcripts have provided the FBI with evidence that Jones or one of his top lieutenants at Jonestown ordered loyalists in Georgetown to kill 10 members of a group of concerned relatives who had stayed behind while others had traveled to Jonestown with Rep. Leo J. Ryan (D-Calif.) on his ill-fated trip.

The peoples Temple radio link from the remote agricultural commune to the Georgetown headquarters was monitored during those final hours by sn American, who said he copied down the coded messages but could not understand them at the time. He agreed to discuss his activities on the condition that he not be identified.

Now the messages have been decoded, based on a Peoples Temple codebook obtained by the FBI, and are being used in the U.S. investigation of events surrounding the death of Ryan at Port Kaituma and the suicide-murder at nearby Jonestown.

The 10 relatives ordered killed were staying at the Pegasus Hotel here and had not yet learned of the congressman's death.

The message, according to informed sources here, was received probably by Sharon Amos, one of the Temple's leaders in Georgetown, who it is believed ordered the killings to be carried out. Amos and her three children were later found dead, their throats slashed, in a bathroom of the cult headquarters.

Why the 10 members of the concerned relatives group were not killed in still a mystery. It is known that Stephen Jones, the Rev. Jones' only natural son, and a group of other cult members did go to the Pegasus to meet with some of the concerned relatives after the message was received. What their intentions were is still a matter of speculation, although it is known, from the radio messages, that the temple headquarters here was not stocked with guns or ammunition.

This is now known because members of the temple group in Georgetown, who were ordered to kill themselves after killing the concerned relatives, radioed back to Jonestown saying that they had nothing to kill themselves with.

A message came back, again in code, spelling out the beginning of the word "knife." According to sources familiar with the decoded messages, only three letters "k-n-i," were transmitted -- apparently enough to get the message across.

This message was received, according to the sources, by three persons then in the radio room at the Georgetown house. Among those there at the time was Lianne Harris, Amos' daughter by a first marriage, who indicated over the radio that she wanted to die along with those at Jonestown, the sources said.

Charles Beikman, a temple member, and Stephen Jones have been charged by Guyanese police with the murders of Amos and her three children. Sources who have knowledge of the radio message transcripts said that, even if Harris indicated she was prepared to die, that would not necessarily mean she and the others were not aided in killing themselves by someone else. Almost everyone familiar with the manner in which Amos and her children died agrees that they could not all have slashed their own throats without assistance.

According to those familiar with the transcripts now in the FBI's possession, the decision to monitor the Peoples Temple radio link was made more by accident than design. The shortwave radio operator in Georgetown said he had inadvertently learned the frequency used by the Peoples Temple and decided to listen in on the communication being sent back and forth because the operator knew that Rep. Ryan was at Jonestown.

When the operator sensed that there might be trouble, largely because of the urgency with which the messages were being sent, be began copying down what he was hearing even though he could not break the code. The operator said he did not copy down all of the messages.

However, Mike Carter, who served as Jonestown's chief radio operator, is still alive and is now in the United States. Carter escaped from Jonestown when he was chosen to be one of three cult members to carry more than a million dollars in cash and various letters to the Soviet Embassy in Georgetown.

Although Junestown is a ghost town occupied only by a detachment of Guyanese police, the headquarters in Georgetown still serves as a residence for about seven cult members who have either chosen not to return to the United States or are being held as material witnesses in the Amos deaths.

Observers here have wondered how remaining members of the Peoples Temple still in Guyana have been supporting themselves. They dine regularly at this city's best restaurants.

One of the Georgetown survivors, Paula Adams, still has contacts with prominent Guyanese, including an ambassador and a well-known attorney. She has said she had an affair with the ambassador.

In another development, it was learned here that Rex McKay, the attorney representing Beikman, Jones and Larry Layton, traveled recently to the United States. Layton has been charged with killing Ryan and four others at Port Kaituma and attempting to kill three other persons in the same attack Nov. 18.McKay reportedly went, in part, to arrange for payment of his legal fees.

Sources said McKay asked one of the defendant's families for $20,000, to be paid to a bank deposit outside Guyana. Whether he received the money or whether he met with anyone else connected to the Peoples Temple while in the United States is not known, the sources said.