Former supermarket worker Alexander Pichushkin confessed to killing 63 people with the goal of marking each death on a chessboard, which has 64 squares.

Prosecutors last month charged him with 49 murders committed between 2001 and 2006 in a park on the edge of Moscow.

Though he claims to have killed several people years earlier, prosecutors had focused on the series of killings that occurred in Bittsa Park in 2001, leading to his nickname as the "Bittsa Maniac." Most of the victims were men, whom Pichushkin had lured to the park with the promise of a drink of vodka to mourn the death of his "beloved" dog.

Pichushkin allegedly killed 11 people in 2001, including six in one month, prosecutors said, adding that he killed about 40 of his first victims by throwing them into a sewage pit and in a few cases strangled or hit them in the head, prosecutors said.

From 2005, he began to kill with "particular cruelty," hitting his intoxicated victims multiple times in the head with a hammer, then sticking an unfinished bottle of vodka into their broken skulls, prosecutors have said. He also no longer tried to conceal the bodies, leaving them at the crime scene.

Thomas' new autobiography, "My Grandfather's Son," shows how the second black justice on the Supreme Court came to oppose affirmative action after his law school experience. He was one of about 10 blacks in a class of 160 who had arrived at Yale after the unrest of the 1960s, which culminated in a Black Panther Party trial in New Haven that nearly caused a large-scale riot.

The conservative justice says he initially considered his admission to Yale a dream, but soon felt he was there because of his race. He says he loaded up on tough courses to prove he was not inferior to his white classmates but considers the effort futile. He says he was repeatedly turned down in job interviews at law firms after his 1974 graduation.

"I learned the hard way that a law degree from Yale meant one thing for white graduates and another for blacks, no matter how much any one denied it," Thomas writes. "I'd graduated from one of America's top law schools, but racial preference had robbed my achievement of its true value."

Thomas says he stores his Yale Law degree in his basement with a 15-cent sticker from a cigar package on the frame.

His view isn't shared by black classmate William Coleman III.

"I can only say my degree from Yale Law School has been a great boon," said Coleman, now an attorney in Philadelphia. "Had he not gone to a school like Yale, he would not be sitting on the Supreme Court."

Coleman's Yale roommate, Bill Clinton, appointed him general counsel to the U.S. Army, one of several top jobs Coleman has held over the years.

Thomas said he began interviewing with law firms at the beginning of his third year of law school.

"Many asked pointed questions unsubtly suggesting that they doubted I was as smart as my grades indicated," he wrote. "Now I knew what a law degree from Yale was worth when it bore the taint of racial preference."

He said it was months before he got an offer, from then-Missouri Attorney General John Danforth.

Steven Duke, a white Yale law professor who taught when Thomas attended Yale, said Thomas is right to say that the significance of someone's degree could be called into question if the person was admitted to an institution on a preferential basis. However, he said that could be overcome by strong performance, noting that two Yale graduates — Danforth and President Bush — put Thomas into top jobs.

"I find it difficult to believe he actually regrets the choice he made," Duke said. "It seems to me he did pretty well."

Some classmates say Thomas — who was raised poor in Georgia and stood out on campus in his overalls and heavy black boots — faced a tougher transition than black students who came from middle-class or privileged backgrounds.

Frank Washington, a black classmate and friend of Thomas who also came from a lower-income background, said he had 42 interviews before he landed a job at a Washington law firm.

"It seemed like I had to go through many more interviews than a lot of my other non-minority classmates," said Washington, now an entrepreneur who owns radio and television stations.

Other black classmates say their backgrounds didn't matter.

Edgar Taplin Jr., raised by a single parent in New Orleans, said he landed a job after graduation at the oldest law firm in New York, and does not recall black graduates struggling more to get jobs than their white classmates.

"My degree was worth a lot more than 15 cents," said Taplin, who retired in 2003 as a global manager with Exxon Mobil.

Thomas has declined to have his portrait hung at Yale Law School along with other graduates who became U.S. Supreme Court justices. An earlier book, "Supreme Discomfort," by Washington Post reporters Kevin Merida and Michael Fletcher, portrays Thomas as still upset some Yale professors opposed his confirmation during hearings marked by Anita Hill's allegations that Thomas sexually harassed her.

Yale Law School Dean Harold Koh turned down requests for interviews about the justice's book, but said in a statement that he and his predecessors have invited Thomas to have his portrait done and the offer still stands.

Koh said they met for several hours about a year ago. "He made it clear that he had greatly enjoyed his time at Yale Law School, and that he had great affection for his fellow students and for several professors who are still here," he said.

Unlike two other security companies operating in Afghanistan and Iraq, Blackwater has said it designates its workers contractors, not employees, because it is a "model that works" and because its guards prefer the "flexibility" of the contractor relationship.

The arrangement has, according to Mr Waxman, wrongly allowed Blackwater to avoid paying social security and Medicare taxes, as well as federal income and unemployment tax - or $32m (£16m) in taxes from May 2006 to March 2007.

The IRS ruling was issued after a single security guard approached the tax authority after a dispute over back pay and other compensation. Although the ruling, which is based on Blackwater exercising control over its worker, applied only to the individual, the IRS alerted Blackwater that it could apply to others.

Blackwater, which has classified 604 security guards as contractors, agreed a settlement with the employee after the ruling. That included a confidentiality agreement that prohibited the employee from contacting "any politician" or "public official" about its details.

"It is deplorable that a company that depends on federal tax dollars for 90 per cent of its business would even contemplate forbidding an employee to report corporate wrongdoing to Congress," Mr Waxman said in a letter to Erik Prince, Blackwater chairman and CEO.

He further alleged that the confidentiality agreement was "particularly suspect" because it was signed by Blackwater general counsel Andrew Howell just as Mr Waxman's committee was stepping up its investigation into Blackwater's activities.

Blackwater said that Mr Waxman's assertions were "incorrect" and took issue with his use of the IRS decision, against which the company has appealed.

The company said the IRS had not made a final determination on the employee and the Small Business Administration had decided Blackwater security contractors were not employees.