Defiant and remorseless as his execution approaches, Timothy J. McVeigh for the first time publicly admits in a new book that he blew up a federal building in Oklahoma City six years ago and coldly refers to the 15 children killed in the building's day-care center as "collateral damage."

McVeigh, 32, also confirms what prosecutors argued at his trial: that he was motivated by his hatred for the federal government.

"I understand what they felt in Oklahoma City. I have no sympathy for them," he told the authors of "American Terrorist: Timothy McVeigh and the Oklahoma City Bombing," during 75 hours of prison interviews.

McVeigh was convicted and sentenced to death in 1997 for detonating a massive truck bomb in front of the Alfred P. Murrah Federal Building, killing 168 people, including 19 children. He has nothing to lose in admitting culpability because he abandoned all his court appeals and is scheduled to die by injection on May 16 at the federal penitentiary in Terre Haute, Ind. He will be the first federal prisoner executed since 1963, when Victor Feguer was hanged in Iowa for kidnapping and murder.

The book is scheduled to be released next week, but authors Lou Michel and Dan Herbeck of the Buffalo News spoke with ABC News's "PrimeTime Thursday," which broadcast excerpts. A spokeswoman for publisher Regan Books said yesterday that McVeigh had no editorial control and was not permitted to review the book before publication.

McVeigh grew up in Pendleton, N.Y., near Buffalo, and met the authors through his father, Bill. McVeigh contends in the book that he had no knowledge that the day-care facility was housed on the second floor of the building, a statement disputed by a defense psychiatrist who evaluated McVeigh, as well as by the FBI's lead investigator in the case.

"If I had known there was an entire day-care center [in the Murrah building], it might have given me pause to switch targets. That's a large amount of collateral damage," McVeigh is quoted as saying.

But psychiatrist John Smith, who spoke to "PrimeTime" with McVeigh's permission, said McVeigh acknowledged in 1995 that he had seen the shadow of a crib in a second floor window when he surveyed the building. In addition, Danny Defenbaugh -- who led the FBI investigation -- told CNN that the bureau believed McVeigh knew of the center because "if you look at the building, you see all the little cut-out hands, all the little apples and flowers," on the windows.

A decorated but disillusioned Persian Gulf War veteran, McVeigh said he bombed the building to avenge the government's 1992 siege at Ruby Ridge, Idaho, when FBI agents killed the wife and a teenage son of separatist Randy Weaver and the 1993 disastrous federal raid on a religious sect near Waco, Tex. McVeigh said he was distraught over the fiery demise of the Branch Davidian compound, when about 80 members of the armed sect died.

"What the U.S. government did at Waco and Ruby Ridge was dirty. I gave dirty back to them at Oklahoma City," McVeigh says, in a reference to the pop song "Dirty for Dirty" by Bad Company.

The authors tell "PrimeTime" that they witnessed McVeigh choke up about once killing a gopher, but that "he never expressed one ounce of remorse" for the Oklahoma City bombing. McVeigh now insists that he was both the sole mastermind and driving force behind the conspiracy. He said that when his co-defendant, Terry L. Nichols, had second thoughts about the attack, McVeigh threatened to kill his family. But legal sources close to the case doubt the accuracy of McVeigh's claim because Nichols never raised coercion in his defense. Nichols was convicted of lesser federal manslaughter charges and sentenced to life in prison; he is awaiting a capital murder trial on state charges.

McVeigh claims he was two blocks away when the explosive detonated, shearing off the front of the building on April 19, 1995, at 9:02 a.m., when workers were just settling into their day.

"The truth is, I blew up the Murrah building," the authors quote McVeigh as saying, "and isn't it kind of scary that one man could reap this kind of hell?"

Timothy J. McVeigh is scheduled to die May 16 in federal penitentiary.