(January 23) -- Theodore Kaczynski, pled guilty Thursday to thirteen federal counts against him for five different bombing attacks attributed to the Unabomber.

In an agreement reached between Kaczynski and the Justice Department, he will spend the rest of his life in prison but will not face a death sentence.

U.S. District Judge Garland Burrell accepted the plea Thursday afternoon in his courtroom at the federal court in Sacramento.

At the hearing, Kaczynski said he was willing to go ahead with sentencing, but once again brought up his ongoing differences with his legal team.

"You know that I have had certain dissatisfaction in my relations with my counsel," he said.

A sentencing hearing is scheduled for May 15, but it is largely a formality.

"It's clear that he will get life sentence without the possibility of release," lead defense lawyer Quin Denvir told Court TV. The government could also fine Kaczynski over $3 million, but Denvir doubted Kaczynski would be fined at all. Kaczynski is prohibited from making any money by writing about his case.

Sources for both sides revealed over the past month that he and his lawyers had been trying since last summer to reach an agreement with the Justice Department in which he would plead guilty in return for being saved from a death sentence.

But talks were reportedly stuck over the issue of whether Kackzynski would have the right to appeal the ruling that allowed federal agents to conduct an initial search of his rural Montana cabin. The final agreement barred any appeal at all by Kaczynski.

Kaczynski had also wanted a commitment that he would not be placed in a federal mental facility, but apparently gave up the attempt to include that detail in the agreement.

However, the apparent turning point for the Justice Department was Dr. Sally Johnson's sealed psychiatric report last week, which sources said indicated that she believed Kaczynski was a paranoid schizophrenic. That was widely believed to be the illness Kaczynski suffered from, but Johnson's report gave the government an official determination of his illness. Mental illness is often a major mitigating factor in death penalty cases, and the government rarely tries to put someone who is mentally ill to death.

Though the issue of mental illness is not common in plea bargain negotiations and rarer still in the scant number of federal death penalty cases that are brought each year, the outcome in this case was not unexpected, said Richard Dieter, director of the Death Penalty Information Center.

"It seemed like a case where the government would naturally accept a plea," said Dieter. "A trial that might have been a mentally ill man defending himself for his life is not something I think anybody relishes."

The plea is also a likely victory for Kaczynski's family, from whom he had been estranged for most of the past three decades. They argued that he was mentally ill and hoped to find a way to keep him from receiving a death sentence. His brother David, who gave the FBI clues that led to the suspected Unabomber's arrest, claimed that he had been duped by federal agents who promised that Ted Kaczynski would not be put to death if he were caught.

David Kaczynski said today that their reaction was "one of deep relief" and called the plea bargain an "appropriate, just and civilized resolution" to the havoc that tore apart their family and the lived of the Unabom victims and their families.

He expressed "deep sorrow and regret" to the survivors of the bombings and told them they had shown "remarkable grace, courage and dignity."

Kaczynski faced ten counts against him in Sacramento for four bombing attacks between 1982 and 1995 in California and Connecticut. A separate indictment was issued against Kaczynski for a 1994 bombing attack in New Jersey. The plea agreement will apparently nullify the second indictment.

The agreement comes directly on top of a decision by Judge Burrell, who was presiding over the Sacramento case, that Kaczynski would not be allowed to represent himself during the trial.

Kaczynski had been battling for months with his lawyers over their strategy to use some form of testimony about Kaczynski's mental state. At one court session in November, he was notably distressed when his mental state was discussed and he wrote numerous letters to Burrell, protesting his lawyers' intentions.

On January 8, after a reported suicide attempt and just before opening arguments were to begin, Kaczynski asked the judge to be allowed to serve as his own counsel. But after getting input from both sides that Kaczynski had the legal right to do so, Burrell denied the request Wednesday, saying that it had not been submitted in a timely manner.

Federal authorities believe that Kaczynski, a 55-year old former Berkeley math professor, was the Unabomber and was responsible for a series of bombing attacks between 1978 and 1995 that killed three people and injured twenty-nine. They coined the name after early attacks targeted university and airline employees.