(CNN) -- An analysis of veins corroborates a confession by a senior al Qaeda leader that he personally beheaded Wall Street Journal reporter Daniel Pearl, according to a new report released Thursday.
Khalid Sheikh Mohammed is suspected of planning the September 11, 2001, terror attacks on the United States.
Mohammed has not denied his role in the killing of Pearl, who was abducted in January 2002.
A video of the journalist's slaying was distributed online nearly a month after he was abducted, but the face of the killer who slit his throat was not visible.
U.S. officials have not charged Mohammed in the 2002 death.
"I decapitated with my blessed right hand the head of the American Jew, Daniel Pearl, in the city of Karachi, Pakistan," Mohammed said, according to a Pentagon transcript released nearly four years ago. "For those who would like to confirm, there are pictures of me on the Internet holding his head."
The new report erases any doubts that Mohammed personally carried out the beheading.
FBI agents and CIA officials used a technique called vein-matching to compare the hand of the killer with a photo of Mohammed's hand, according to the report.
Mohammed told the FBI that a senior al Qaeda operative advised him to take control of Pearl from his original kidnappers, the report said.
Pearl was seized on his way to what he believed was an interview with a radical cleric. At least 27 men played a role in the kidnapping and death -- 14 of whom are believed to be free, the report said.
At least three different militant groups were involved in the crime, including kidnappers led by British-Pakistani Omar Sheikh and a team of killers led by Mohammed, according to the report.
It also highlights the hurdles authorities faced in the investigation, including contradictory evidence.
Pakistani authorities freed a guard, who was a key informant, and failed to follow potential leads, according to the report.
The three-year Pearl Project was prepared by faculty and students at Georgetown University in Washington D.C. It was released Thursday by the Center for Public Integrity.
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