Maryland state police said yesterday they are investigating the possibility that retired CIA official John A. Paisley was shot while in the water or on another vessel in the Chesapeake Bay.

"I doubt very much anyone killed him-or he killed himself-on his (Paisley's) boat," said Capt. Paul Rappaport, head of a seven-man police team investigating the birarre death.

Paisley's body, weighed by two diving belts and shot in the head, was discovered floating in the bay last week.

"There was no evidence . . . that his boat was the crime scene - no bloodstains and no brain fragments," Rappaport said.

Asked if Paisley could have been taken off his boat and shot on another vessel, Rappaport said: "It's a possibility."

The death of the 55-year-old retired CIA analyst, whose body was found after his abandoned sailboat ran aground near Point Lookout, Md., continues to baffle authorities who say they don't know whether Paisley was murdered or committed suicide.

"If the man took his own life," said Maryland State Police Superintendent Thomas S. Smith yesterday, "he went to great lengths to cover it up. If someone else did, they seized upon an unusual scene and carried it out in an unusual way."

Although police have not ruled out suicide, the fact that seven investigators have been assigned to the case indicates that police are treating it with high priority. This is "something we would not normally do in a suicide," Rappaport said yesterday.

According to Rappaport, Paisley may have been a piracy victim. "One month ago on the Chesapeake, we received reports that a boat was hijacked, with people hit over the head and thrown in the water," said Rappaport. Police are pursuing the possibility that Paisley may have been such a victim, he said.

Rappaport said the absence of any evidence of a shooting on Paisley's 31-foot sloop Brilling may indicate that the victim was shot - or shot himself - in the water. "He could have been hanging outside the boat holding on with one hand and shot himself with the other," the investigator said.

No gun has been recovered and Rappaport said yesterday that if the weapon was thrown or dropped into the bay, "We'll probably never find it."

One Coast Guardsman, Wayne Ward, who boarded Paisley's vessel the morning after it was found, said yesterday, "I don't see how it (the shooting) could have been done on board. To me, there would have to have been some sort of evidence - no matter how slight. If it did happen there, it got cleaned up by itself. It didn't rain that night."

Rappaport said yesterday that officers from a mobile crime lab first went on board the vessel Friday, an action that several other investigators pointed out should have occured earlier. "The problem is that any evidence would be contaminated. It should have been done on Monday. I made the decision to have them go down anyway," Rappaport said.

Asked about fingerprints, Rappaport said: "I would assume that they did take prints. I have not received the report yet."

Paisley's boat was discovered "in disarray" according to one coast guardsman from the Portsmouth Rescue Center, who said the drifting sailboat was spotted by another sailor who called a park ranger. A Coast Guard vessel arrived on the scene, followed by Paisley's estranged wife, Maryann, and agents from the CIA. The Maryland state police were called in several days later, after his body was discovered."

According to witnesses, canned goods, cigarette butts and a change of clothing were found on Paisley's boat. Rappaport said yesterday that the clothes belonged to Paisley.

Earlier this week, the Senate Intelligence Committee began an investigation into alleged links between paisley's death and the theft of secret CIA documents - a theory the CIA has labeled "absurd."

"Everyone wants to believe there's a UFO with Russian agents on it in the bay sucking up CIA agent . . . Everybody wants to believe there's something cloak-and-dagger about it," said Maryland police spokesman William Clark. "The truth is that nobody has the complete facts."

Police are baffled by the second weight belt found on Paisley's body. "It was not the same type as the one identified as belonging to the victim," Smith said yesterday.

Paisley - an experienced sailor and scuba diver - was known to have owned only one weight belt, police say.

"Obviously, whoever killed him - if Paisley was in fact murdered - was not a waterman," Smith said nothing that it would take more than 38 pounds to prevent a bloated body from surfacing.

"This is an unusual case. Maybe we'll never know what happened." Smith said. "It's a challenge. If it's necessary we'll put additional people on it."