He was arrested and served time in prison for the 1994 abduction of several British nationals in India, an act which he acknowledges, he was released from captivity in 1999 and provided safe passage into Pakistan, apparently with the support of Pakistan and the Taliban (the hijackers were Pakistanis) in an Indian Airlines plane hijacking. He is most well-known for his alleged role in the 2002 kidnapping and murder of Wall Street Journal reporter Daniel Pearl. Sheikh Omar Saeed was arrested by Pakistani police on February 12, 2002, in Lahore, in conjunction with the Pearl kidnapping, and was sentenced to death on July 15, 2002 for killing Pearl. His judicial appeal has not yet been heard. The delay has been alleged to be due to his reported links with Pakistan's Inter-Services Intelligence.
Former Pakistani President, Pervez Musharraf, in his book In the Line of Fire stated that Sheikh was originally recruited by British intelligence agency, MI6, while studying at the London School of Economics. He alleges Omar Sheikh was sent to the Balkans by MI6 to engage in jihadi operations. Musharraf later went on to state, "At some point, he probably became a rogue or double agent".
His complicity in the execution and the reasons behind it are in dispute. At his initial court appearance, he stated, "I don't want to defend this case. I did this... Right or wrong, I had my reasons. I think that our country shouldn't be catering to America's needs.", but he subsequently appealed his conviction and is awaiting further progress while in prison. Sheikh's lawyer has stated he will base his client's appeal on the recent admission of Khalid Sheikh Mohammed that he is the killer of Daniel Pearl.
In May 2002, the Washington Post quotes an unnamed Pakistani as saying that the ISI paid Sheikh's legal fees during his 1994 trial in India on charges of kidnap. However, this claim has not been confirmed by any other source.
US authorities have also named Saeed Sheikh as a key figure in the funding of the 9/11 attacks.

The 9/11 Commission's Final Report states that the source of the funds "remains unknown."
More than a month after the money transfer was discovered, the head of ISI, General Mahmud Ahmed resigned from his position. It was reported that the FBI was investigating the possibility that Gen. Ahmed ordered Saeed Sheikh to send the $100,000 to Atta
; there were also claims that Indian intelligence had already produced proof for the Pakistani administration that this was so.
The Wall Street Journal was one of the only Western news organizations to follow up on the story, citing the Times of India: "US authorities sought General Mahmud Ahmed's removal after confirming the fact that $100,000 was wired to WTC hijacker Mohammed Atta from Pakistan by Ahmad Umar Sheikh at the instance of General Mahmud."
Another Indian newspaper, the Daily Excelsior, quoting FBI sources, reported that the "FBI’s examination of the hard disk of the cellphone company Omar Sheikh had subscribed to led to the discovery of the "link" between him and the deposed chief of the Pakistani ISI, Mahmud Ahmed. And as the FBI investigators delved deep, sensational reports surfaced with regard to the transfer of 100,000 dollars to Mohammed Atta, one of the terrorists who flew his Boeing into the World Trade Center. General Mahmud Ahmed, the FBI investigators found, fully knew about the transfer of money to Atta."
The Pittsburgh Tribune notes that there "are many in Musharraf's government who believe that Saeed Sheikh's power comes not from the ISI, but from his connections with our own CIA."
Sheikh rose to prominence with the 2002 killing of Wall Street Journal reporter Daniel Pearl, who at the time was in Pakistan investigating connections between the ISI and Islamic militant groups. In Pakistan, Sheikh was sentenced to death for killing Pearl, however his complicity in the execution and the reasons behind it are in dispute.
In an opinion piece published by the Wall Street Journal, Tunku Varadarajan has claimed that “It is a fact that General Mahmud Ahmed, then head of the ISI, wired $100,000 to Mohammed Atta before 9/11 through an intermediary.
Sheikh Omar Saeed was arrested by Pakistani police on February 12, 2002, in Lahore, in conjunction with the Pearl kidnapping, He told the Pakistani court, however, that he had surrendered to the Inter-Services Intelligence Agency a week earlier.
Charlie Wilson's War - "The Israeli Jihad Connection".]