A political campaigner from north London, tipped for a glittering career, has been stabbed to death in the US.
Mr Senitt was described as "an outstanding young man"
Police said Alan Senitt, 27, was trying to protect his female companion when they were targeted by armed robbers as they walked home in Washington DC.
The former chairman of the Union of Jewish Students (UJS), from Pinner, had moved to the US to work on Democrat Mark Warner's presidential campaign.
Two men, a youth and a woman have been charged with murder.
A 25-year-old man has also been charged with attempted assault on Mr Senitt's female friend.
Washington Police spokesman Sergeant Joe Gentile told the BBC News website: "The suspects demanded money and property.
"Then one of the suspects attempted to sexually assault the female."
After the attack in the Georgetown area at 0200 local time on Sunday, the three attackers got into a waiting car and drove off.
Two men, aged 22 and 25, a youth, 15, and a woman, 26, were arrested shortly afterwards.
Mr Senitt's parents Jack and Karen, who live in Pinner, north London, said the brutal death of their eldest son had left them devastated.
"It will take us a lifetime to come to terms with our tragic loss," the family said in a statement.
"We have lost a much-loved son and brother.
"The Jewish community as a whole has lost one of its bright young leaders and the wider world has lost a champion of peace and goodwill."
The Birmingham University graduate had recently completed a course in diplomacy at the School of Oriental and African Studies in London.
He had stood as a Labour candidate in the Edgware ward in north London and was about to start working for former Virginia governor Mr Warner.
He had also been the UJS representative to the Board of Deputies of British Jews, which said his move to Washington DC "should have been a further step in a glittering career".
"We deeply mourn his loss and send our heartfelt condolences to his family and friends," it added.
Jeremy Newark, head of the Jewish Leadership Council, said: : "Alan became a true friend of those that he worked with.
"He was an outstanding and passionate advocate for Israel, whilst articulating a message of tolerance and co-existence."