— July 30, 1975: Hoffa leaves his Lake Orion home about 1 p.m. and makes a stop to visit a friend in Pontiac. He arrives around 2 p.m. at the Machus Red Fox restaurant in Oakland County's Bloomfield Township to meet reputed Detroit mob enforcer Anthony "Tony Jack" Giacalone and alleged New Jersey mob figure Anthony "Tony Pro" Provenzano. Hoffa calls his wife, Josephine, about 2:15 p.m. from a pay phone and tells her no one showed up for his meeting. The 62-year-old Hoffa never is seen or heard from again.
— July 31, 1975: Hoffa's green Pontiac Grand Ville is found, unlocked, in the restaurant parking lot. The Hoffa family files a missing person report with the Bloomfield Township police.
— Aug. 2, 1975: The FBI takes over the investigation.
— Aug. 8, 1975: The FBI gets a search warrant for the car. They find fingerprints of family friend Charles "Chuckie" O'Brien on a 7-Up bottle under the right front seat and a piece of paper in the glove compartment.
— Aug. 21, 1975: Police dogs sniff the shorts Hoffa wore the day before his disappearance and indicate Hoffa's scent was in the rear of a car O'Brien borrowed from his friend Joe Giacalone, son of Anthony Giacalone.
— Sept. 2, 1975: A grand jury convenes in Detroit to investigate the Hoffa disappearance.
— 1975-85: More than 200 FBI agents are assigned to the case in New Jersey, Detroit and at least four other cities. During the period, more than 70 volumes of files are compiled, containing more than 16,000 pages. Six suspects in the disappearance, including Provenzano and Anthony Giacalone, are convicted on unrelated charges.
— 1982: Self-described mafia murderer Charles Allen, who served prison time with Hoffa and participated in the federal witness-protection program, tells a U.S. Senate committee that Hoffa was killed at Provenzano's orders. Hoffa's body was "ground up in little pieces, shipped to Florida and thrown into a swamp," Allen said.
— 1982: Hoffa is declared legally dead.
— 1989: Kenneth Walton, who headed the Detroit FBI from 1985 to 1988, tells The Detroit News that he knows what happened to Hoffa: "I'm comfortable I know who did it, but it's never going to be prosecuted because ... we would have to divulge informants, confidential sources."
— 1989: Hoffa's daughter, Barbara Ann Crancer, files a Freedom of Information Act lawsuit against the FBI, demanding the agency's reports on her father's disappearance.
— 1989: Self-described hit man Donald "Tony the Greek" Frankos claims Hoffa is buried under Giants Stadium in East Rutherford, N.J. The FBI finds no evidence to support the claim.
— 1993: The U.S. Court of Appeals reverses a ruling ordering the FBI to turn over files on the Hoffa investigation to Crancer.
— November 2000: Current and former FBI agents and federal prosecutors meet in Detroit to discuss prosecutorial strategy and the current state of the Hoffa investigation.
— March 2001: A second meeting is held after DNA tests find a match between a hair found in the back of the car driven by O'Brien and a hair in Hoffa's hairbrush.
— June 2001: The head of the FBI's organized-crime unit says in a court document that he believes a decision whether to prosecute anyone could be made in the next two years.
— March 2002: The FBI says it will refer the case to the Oakland County prosecutor's office for possible state charges. John Bell, special agent in charge of the FBI's Detroit bureau, says the federal case was stymied because of the length of time since Hoffa disappeared.
— Aug. 29, 2002: Oakland County prosecutor says new DNA evidence in Hoffa's disappearance is insufficient to bring criminal charges.
— July 16, 2003: Authorities dig beneath an underground pool at a home in Michigan's Thumb area for a briefcase an informant says contained a syringe and possible evidence that Hoffa might have been injected with drugs or poison. No briefcase is found.
— May 2004: Bloomfield Township police rip up the floorboards from a Detroit house where one-time Hoffa ally Frank Sheeran claims to have killed him. The FBI crime lab would ultimately conclude that the blood found on the floorboards was not Hoffa's.
— April 2006: New Jersey mob hit man Richard "The Iceman" Kuklinski, who died in March, claims that he killed Hoffa and put his body in a car that was sold as scrap metal. Kuklinski's book, "The Ice Man: Confessions of a Mafia Contract Killer," contends he received $40,000 for the slaying.
— May 17, 2006: The FBI begins searching a horse farm in Oakland County's Milford Township, northwest of Detroit for Hoffa's remains.
— May 30, 2006: The FBI says it has ended the search at the horse farm, having found nothing. However, an agent says she believes that Hoffa was buried there at one point.
— September 2012: Authorities drill for soil samples in the floor of a shed in the Detroit suburb of Roseville after police are told by a source that Hoffa was buried beneath the driveway. Tests showed nothing.
— June 17, 2013: The FBI sees enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for Hoffa's remains in an Oakland Township field, about 25 miles north of Detroit.
— June 19, 2013: FBI says no remains of Hoffa found at Oakland Township site.