A new report on the murder of Wall Street Journal reporter Daniel Pearl reveals that U.S. officials used a forensic technique called vein analysis to corroborate the confession of the self-professed killer, Khalid Sheikh Mohammed, who also is suspected of planning the Sept. 11, 2001, attacks on the U.S.

The report details problems in bringing to justice others suspected of involvement in the crime, including the recent release by Pakistan of a man thought to have been one of the main players.

The report is the work of the Pearl Project, a three-year endeavor to answer lingering questions surrounding Mr. Pearl's death. The project was led by former Journal reporter Asra Q. Nomani, who worked with faculty and students from Georgetown University. It is being published Thursday by the Center for Public Integrity, a Washington-based investigative-journalism organization.

Mr. Pearl, who was 38 at the time of his death, was abducted Jan. 23, 2002, by Islamist militants in the crowded and chaotic Arabian Sea port of Karachi, while reporting on terrorism.

The report shows that, despite the widespread attention his case garnered, the precise story of Mr. Pearl's final days and the exact timing of his death remain shrouded in a fog of conflicting confessions and testimony by alleged perpetrators, their compatriots and Pakistani investigators.

By most accounts, Mr. Mohammed wasn't part of the original plan to abduct Mr. Pearl. He told U.S. investigators that he was pulled in later by another senior al Qaeda operative.

Mr. Mohammed was asked to take over because the kidnappers — midlevel and low-level Pakistani militants — didn't know what to do with Mr. Pearl. Mr. Mohammed's involvement presented al Qaeda with an opportunity for what it saw as a propaganda victory, the report says, citing investigators who interrogated Mr. Mohammed.

In October 2003, U.S. officials disclosed that Mr. Mohammed, while in American custody, had confessed to the killing.

Click here for more on this report from The Wall Street Journal.