If killer nurse Charles Cullen stops cooperating with a probe into his crimes, New Jersey authorities say, they'll withhold the one thing they have that he really wants: permission to donate a kidney to an ailing acquaintance.

Cullen notified authorities earlier this week that he would no longer cooperate in identifying his victims because he is angry that his sentencing was postponed indefinitely while prosecutors in Essex and Morris counties try to decide whether to charge him with additional murders.

In newspaper reports published Wednesday, his lawyer, Johnnie Mask, said Cullen would renew his efforts to avoid appearing at his sentencing, denying relatives of his victims their long-sought chance to confront him in court.

"The deal is off," Mask said. "He's done. No more cooperation. Period."

Mask did not return a call from The Associated Press seeking comment Wednesday.

Cullen, the state's worst serial killer, still could face a death penalty prosecution if it is discovered he murdered more than the 22 patients he already has admitted slaying in New Jersey. The state, however, has a moratorium on executions and hasn't put anyone to death since 1963.

Cullen has pleaded guilty to 29 murders and six attempted murders in New Jersey and Pennsylvania, and has told investigators he might have killed as many as 40 people. In most cases, he gave patients an overdose of heart medication, usually digoxin.

On Wednesday, prosecutors said they plan to use the kidney operation as leverage over the 45-year-old former critical care nurse, who wants to be able to travel to New York to donate the organ.

The state has insisted Cullen appear at his sentencing to face his victims' families before being permitted to donate a kidney to a recipient whose name has not been made public, but is reportedly a relative of a former girlfriend.

"We don't care if Charles Cullen donates a kidney to anyone," Attorney General Peter Harvey said Wednesday. "He's either going to die in jail or pursuant to the death penalty. It doesn't matter to us."

Whether Cullen is present for his sentencing ultimately is up to a judge. After he is sentenced in New Jersey, he faces sentencing for seven murders in Pennsylvania.