Civil rights leader Martin Luther King was assassinated in Memphis, Tennessee, 40 years ago on 4 April 1968.

A year later, James Earl Ray admitted to being the assassin. Because of that guilty plea there was no full trial. But Ray changed his story almost at once and until his death in 1998 insisted he did not murder Dr King. So was he the killer? And if so, did he work alone?

The military is using the FBI to skirt legal restrictions on domestic surveillance to obtain private records of Americans’ Internet service providers, financial institutions and telephone companies, according to Pentagon documents.

The American Civil Liberties Union expressed outrage at the new revelations, based its conclusion on a review of more than 1,000 documents turned over by the Defense Department after it sued the agency last year for documents related to national security letters, or NSLs, investigative tools used to compel businesses to turn over customer information without a judge’s order or grand jury subpoena.

The almost fanatical zeal with which the FBI pursued King is disclosed in tens of thousands of FBI memos from the 1960s.

The FBI paper trail spells out in detail the government agency’s concerted efforts to derail King’s efforts on behalf of the civil rights movement.

The FBI’s interest in King intensified after the March on Washington in August 1963, when King delivered his “I have a dream speech,” which many historians consider the most important speech of the 20th century. After the speech, an FBI memo called King the “most dangerous and effective Negro leader in the country.”

Don’t forget this CNN story from 1999

Five years ago, Congress killed an experimental Pentagon antiterrorism program meant to vacuum up electronic data about people in the U.S. to search for suspicious patterns. Opponents called it too broad an intrusion on Americans’ privacy, even after the Sept. 11 terrorist attacks.

But the data-sifting effort didn’t disappear. The National Security Agency, once confined to foreign surveillance, has been building essentially the same system.

Several thousand law enforcement agencies are creating the foundation of a domestic intelligence system through computer networks that analyze vast amounts of police information to fight crime and root out terror plots.

As federal authorities struggled to meet information-sharing mandates after the Sept. 11, 2001, terrorist attacks, police agencies from Alaska and California to the Washington region poured millions of criminal and investigative records into shared digital repositories called data warehouses, giving investigators and analysts new power to discern links among people, patterns of behavior and other hidden clues.