Abraham Badru, 26, was gunned down in Hackney, east London, on 25th March after opening the boot of his car to look for a drink, police said.
Paramedics and police were called to the scene in Ferncliff Road, but Mr Badru was pronounced dead.
Churchgoer Mr Badru had previously received a bravery award for intervening in a sex attack on a teenage girl and his family said the pain of losing him is "unbearable".
They added: "Abraham hates confrontation, he has never been involved in any fight be it physical or verbal, not to talk of being involved in a gang or condoning gang violence.
"An avid church-goer, a God fearing young man, this is why it's hard to comprehend why anyone would want to hurt him and cause a void that could never be replaced or recreated, why would anyone lurk and wait to carry out such a brutal attack?
"He steered clear from trouble, loved life too much to risk it in any way. He just wanted to be happy and continue to make his parents happy and his loved ones.
"Abraham has been snatched from us; he didn't die of an illness, a freak accident, or of natural causes, no death is ever easy but he died because he was shot.
"He was shot by person/persons terrorising the peace of the community, terrorising innocent people, threatening our freedom on our streets and threatening our progression.
"We plead with any parent, siblings, extended family, friends, associates, in desperation that if you have any information to please come forward."
The investigation into Mr Badru's murder is one of 48 inquiries Scotland Yard has launched so far this year - eight in January, 15 in February, 22 in March and two in April.
The Metropolitan Police said just before the attack - at around 11.10pm - Mr Badru had parked his black Mercedes on Ferncliff Road when he was approached by a suspect or suspects.
A black male, believed to be wearing a black puffer jacket, walked along Ferncliff Road in the direction of Downs Park Road and through a nearby alleyway after the sound of a gunshot, officers added.
Police said Mr Badru - described as a "talented young man with ambitions and so much to live for cut down in his prime" - was not intending to be home and his return was due to a change of plans.
Detective Chief Inspector Noel McHugh said: "The answer to Abraham's death lies in the community. I know that people are talking about what happened.
"It is something truly out of the ordinary, a community hero being murdered.
"His family and friends cannot comprehend what has happened, and there are no words that can adequately describe the pain Abraham's family are going through.
"Abraham was a striking young man and a real contributor to society. He was awarded a National Police Bravery Award in 2009 after intervening in a rape and then giving evidence in court.
"Such courage and an overwhelming sense of what was right and wrong clearly demonstrated his strength of character."
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