Warren Commission investigator who proposed the single-bullet theory
Arlen Specter, who died on October 14 aged 82, came to prominence as an assistant counsel to the Warren Commission investigating the assassination of President John F Kennedy in Dallas in 1963; he later became a US senator, first as a Democrat, then as a Republican and finally as a Democrat again.
On the Warren Commission, Specter was the principal architect of the single-bullet theory in Kennedy's assassination. This posited that the same bullet had struck both Kennedy and Texas governor John Connally, an assumption crucial to the conclusion that the assassin Lee Harvey Oswald had acted alone. The theory remains controversial and was ridiculed in Oliver Stone's 1991 film JFK.
Having switched from the Democrats to the Republicans early in his political career, Specter astonished fellow senators in 2009 by rejoining the Democrats, explaining that he was "increasingly at odds with the Republican philosophy".
Fiscally conservative but socially liberal, Specter consistently voted against plans by the Reagan administration in the Eighties to cut welfare benefits and worked to defeat President Bill Clinton's national healthcare plan. In 1995 he launched a bid for the US presidency, denouncing religious conservatives for playing too prominent a role in setting the Republican agenda, but later withdrew for want of financial support.
The son of Russian-Jewish immigrants, Arlen Specter was born in Wichita, Kansas, on February 12, 1930, and spent school holidays working in his father's scrapyard. Specter graduated from the University of Pennsylvania in 1951, served in the US Air Force from 1951 to 1953, and took a Law degree at Yale in 1956.
Entering politics as a Democrat in 1959, he was appointed an assistant district attorney in Philadelphia and earned a reputation as a tough prosecutor when he secured convictions for corruption against six officials of the Teamsters union.
After the Warren Commission, he became district attorney in 1965, standing on a Republican ticket in a predominantly Democrat city. One of his more eye-catching initiatives, in an attempt to defuse tensions between rival teenage gangs, was to appoint two warring gang leaders to his office as "consultants".
But critics complained that Specter so craved publicity that, as one remarked: "Someone spills a can of beans, Arlen will issue a statement."
When Specter failed to be re-elected in 1973 he went into private practice. In 1980 he won a seat in the Senate, and as chairman of a judicial subcommittee on juvenile justice again caught the media's attention by taking evidence from former porn star Linda Lovelace and children's television show host Captain Kangaroo. Specter retained his Senate seat until last year.
He also occasionally performed standup comedy at clubs in Philadelphia and New York. He played squash nearly every morning until he was in his mid-70s.
Arlen Specter married, in 1951, Joan Levy, with whom he had a son and a daughter.