Allen M. Dorfman, who was convicted last month of conspiring to bribe a U.S. senator to do favors for the Teamsters union, was shot to death today in what appeared to be a gangland execution.

A millionaire insurance executive long suspected of being a middleman between some union figures and the Mafia, Dorfman, 60, was killed in the parking lot of the suburban Lincolnwood Hyatt Hotel as he walked with a friend toward the hotel's coffee shop, police said.

The man with Dorfman, a former bail bondsman and business associate, Irwin S. Weiner, was not injured, although one officer said at least eight shots were fired.

"They were approached from behind by two men," said Lincolnwood police officer Donald Kufner. One of the assailants reportedly announced that "this is a stickup," but Kufner said the shooting started as soon as Dorfman and Weiner turned around.

Police said Dorfman was hit in the head by a .22-cal. bullet, evidently from a semi-automatic weapon wielded by one of the attackers, and fell to the ground.

"The guy kept pumping bullets into him," Kufner said. "They didn't try to make it a real stickup."

There were conflicting reports on what the killers looked like and how they escaped.

Lincolnwood police said, "The report we have is that one was a white man and one was a black man," but another witness suggested later that the attackers might have been wearing ski masks. In addition, police reported, "Somebody said they ran off. Another witness said they drove off."

The murder prompted speculation that Dorfman may have been killed "to keep him quiet," as the Chicago Crime Commission's executive director, Patrick Healy, put it.

Depicted in FBI memos and court records as "controlled" by the Chicago crime syndicate, Dorfman was scheduled to be sentenced Feb. 10 for plotting to bribe former senator Howard W. Cannon (D-Nev.), and was facing trial on two other indictments stemming from the same investigation that led to last month's conviction.

"Look at his track record," Healy said of Dorfman. "Look at the trouble he's been in, the people he's been involved with, the miscellaneous federal agencies looking at him. He finally gets convicted. He's facing heavy time. He's 60. I think he asks himself, 'What do I do to get out from under?' "

At the same time, both Dorfman's attorneys and federal authorities denied that Dorfman had been cooperating with the government or that any overtures had been made. Several lawyers said it would have been premature in any case to have approached Dorfman prior to sentencing.

The killing was "an absolute shock," said Royal Martin, a partner in the law firm that defended Dorfman in the Teamsters bribery-conspiracy trial. "We heard nothing of any threats being made against Allen's life, and we knew of no reason why he should fear for his life."

A behind-the-scenes power in the Teamsters' Central States Pension Fund for more than 30 years, Dorfman was convicted Dec. 15 with four other men, including Teamsters union President Roy Lee Williams and reputed mobster Joseph (Joey the Clown) Lombardo, who allegedly "controlled" Dorfman for the Chicago crime syndicate.

After the trial, Williams openly repudiated Dorfman, attacking him in a Dec. 20 Kansas City Times interview as a "braggart" who "manipulated" others to further his own interests.

Williams said he had approved action to oust Dorfman from his remaining $10 million-a-year business in processing Central States Health and Welfare Fund claims. The Teamsters boss predicted that Dorfman's Amalgamated Insurance Agency would be cut off within two months.

"He's gone by Feb. 1," Williams told The Kansas City Times, in what stands now as an uncomfortably prophetic quote.

The FBI announced this afternoon that it had entered the case at the request of Lincolnwood police and was investigating possible violation of the federal anti-racketeering statute. "Murder in furtherance of a criminal enterprise is a federal offense," a spokesman said.

A wealthy man who rose to influence through his stepfather, Paul (Red) Dorfman, a reputed labor racketeer who launched his career during the days of Al Capone and continued under the late Teamsters president Jimmy Hoffa, Dorfman lived in a $750,000 home in suburban Deerfield.

He had a 167-acre hunting and fishing lodge near Eagle River, Wis., and a $350,000 second home in La Costa, Calif.

Dorfman was freed before sentencing after posting a $1 million cash bond and pledging more than $10 million worth of stock in his insurance companies as additional collateral.

Before his recent conviction Dorfman had been found guilty in a 1972 case involving a $55,000 kickback from a pension fund loan, but was acquitted on several other occasions, including the 1960s jury-tampering case that put Hoffa in prison.

In another trial in Chicago in 1975, Dorfman, Weiner and several other men were acquitted of charges of defrauding the Teamsters pension fund in connection with $6 million in loans.

Lombardo was to have been tried with them, but the charges against him were abandoned before trial, after the 1974 murder of a key witness. Two men wearing ski masks burst in on the witness, Daniel Seifert, in front of Seifert's wife and baby, and chased him toward another gunman, who shotgunned Seifert in the head.