Mr Kallstrom confirmed on Wednesday night that the FBI had sent the letter to the victims' families, but he gave no details "as it is a private matter between the FBI and the families at this point". The FBI plans to hold a news conference next week to issue a comprehensive report on the criminal probe's findings, a law-enforcement source said.
Mr Kallstrom wrote that the FBI would continue to be involved in the investigation by the National Transportation Safety Board (NTSB) of the July 1996 crash of the Paris-bound aircraft. "Every lead has been covered, all possible avenues of investigation exhaustively explored and every resource of the United States government has been brought to bear in this investigation," he said.
The NTSB is continuing to try to learn what caused vapours inside the empty fuel tank to explode, shattering the aircraft shortly after take- off from Kennedy Airport in New York. The FBI has said repeatedly it has found no evidence that the Boeing 747 was downed by a bomb or missile.
The FBI began its investigation minutes after the jumbo jet burst into a fireball, killing everyone on board and scattering wreckage across a five-square-mile area of the Atlantic Ocean, about 10 miles off Long Island. Eyewitnesses reported streaks of light in the sky just before the explosion, prompting a team of investigators to focus on the missile theory. The FBI flatly rejected allegations by conspiracy theorists that an errant US Navy missile was to blame.
"When it first happened, I thought bomb," said Joe Lychner of Houston, who lost his wife and two small daughters in the crash. "But when I look at all the testing the FBI did and they found nothing, I am convinced this had to be mechanical."
FBI agents interviewed more than 7,000 people, including everyone who touched or had access to the aircraft at Kennedy Airport and in Athens, Greece, where the flight originated. The FBI and NTSB reconstructed the wreckage inside a hangar and then scrutinized the holes and punctures for any evidence of a crime.
Michel Breistroff of Paris, whose 25-year-old son was killed, said he received Mr Kallstrom's letter on Wednesday. He said he and other family members overseas now plan a campaign to have all 747s grounded. "This plane is obviously a dangerous plane," he said. "It took investigators all these months and all these millions of dollars to tell us that."
TWA spokesman Donn Walker in St Louis said the airline did not know the FBI had sent letters indicating that it was ending its criminal investigation. "They've been hinting for a while so it's really not a surprise," he said. He added that the company was frustrated that federal investigators have not been able to determine what caused the crash. "We just want answers. We just want to know what happened."Reuse content