The three secret police officers accused of murdering the Rev. Jerzy Popieluszko say they had not meant to kill the outspoken priest but ended up assaulting him when the kidnaping went awry, a government spokesman said today.

Providing new details about the death, spokesman Jerzy Urban said the three functionaries claim to have intended only to threaten the pro-Solidarity cleric but were panicked into killing him by a series of "misfortunes" during the abduction.

"They say they committed this murder because they lost their heads. They had no intention of killing him," Urban told reporters.

Findings of the official investigation into the priest's death have been publicized almost daily by the authorities. Today's disclosures included a number of more specific and dramatic elements than were reported yesterday in a lengthy account to a parliamentary committee by Interior Minister Czeslaw Kiszczak.

These daily revelations may reflect the piecemeal nature of the investigation. But they also serve the government's interest in appearing to be open and hard at work piecing together the facts of a case that has horrified the nation, galvanized the opposition and disrupted church-state relations.

Urban's press conference did little to shed light on the meaning of Tuesday's announcement by the Communist Party's ruling Politburo that the party's leader, Gen. Wojciech Jaruzelski, had assumed direct responsibility for party activities in the Interior Ministry, which controls Poland's police forces.

The spokesman said only that the move would allow Jaruzelski to exercise political supervision over the ministry along with the administrative supervision he has exercised in his capacity as prime minister.

An informed party official said privately that the change represented a setback for Miroslaw Milewski, the party boss formally responsible for supervising the security services. A career policeman, Milewski is identified with the party's hard-line wing.

Polish authorities have indicated that they intend to determine political responsibility as well as criminal responsibility for Popieluszko's killing. This has been taken as signaling a purge of hard-line elements that have advocated the use of force and repression over the sometimes more pragmatic, cautious course favored by Jaruzelski and his associates. Speculation has focused on Milewski as a likely political scapegoat.

The Politburo's announcement of Jaruzelski's additional role made no mention of a change in Milewski's status. Communist officials said today that the situation should become clearer at the next meeting of the party's Central Committee, due before the year's end. Until then at least, they said, Milewski is expected to retain his seat on the Politburo and his title as party secretary in charge of the security services.

On the Popieluszko kidnaping, Urban said the investigation found that the operation was bungled: The driver of Popieluszko's car, Waldemar Chrostowski, who had been handcuffed, gagged and shoved into the abductors' car, managed to jump out and escape; the kidnapers' car broke down while Popieluszko, who was in the trunk, began shouting and banging; the kidnapers were stopped for a routine road check by traffic police, and Popieluszko at one point attempted to flee from the abductors, prompting them to beat him, according to their testimony.

The priest's corpse, bruised, bound and gagged, was retrieved from a reservoir at Wloclawek, northwest of Warsaw, last week.

"It may be assumed, as they are now suggesting, that they only wanted to threaten Popieluszko and that perhaps they committed the crime because of a series of misfortunes that happened during the abduction," Urban said of the perpetrators. "They claim that under the influence of those misfortunes, they became scared and started to behave carelessly."

But Urban also cautioned against taking the suspects' statements "at face value," noting that the kidnaping had been extensively planned for some time. He said the three officers had first tried on Oct. 13 -- six days before the actual abduction -- to seize the priest by flagging down his car midway between Warsaw and the northern port of Gdansk. But Popieluszko did not stop then.

Urban said the investigation has turned up several curious facts about the alleged ringleader, Capt. Grzegorz Piotrowski -- in particular, that he recently purchased two expensive foreign cars, an Audi and a Fiat 132, with the help of someone in the West, and that he had a dollar account, although only a small amount was on deposit.

The spokesman declined to draw any conclusions from such evidence. Asked if authorities suspected that western intelligence agencies may have set up the crime, Urban said there was no evidence of such involvement but "every possibility is being checked out."

One of the possibilities raised by the Solidarity opposition is that the functionaries who attacked Popieluszko may have been part of a wider network of "hit squads" operating against opposition circles.

Several activists in the Torun area, where Popieluszko was ambushed, have told of kidnapings and beatings in February and March this year by men having ties to the secret police. Official investigations of these cases were terminated by a local prosecutor Oct. 5, Urban said today, for lack of evidence. The cases are on appeal.