A knifeman struck in seconds to murder a man walking home from a friend's house in north London on Saturday.
Mr Brown was killed the day before his 28th birthday
Detectives believe BBC employee Tom Brown, 27, had no time to react before he was killed in Southgate at 0300 BST.
Robbery has been ruled out as his phone and money were with his body, found yards from his home at 0430 BST.
Det Ch Insp Keith Garnish said the killer had "the ability and desire to kill someone very quickly and in an unprovoked attack".
He added: "The individual who carried out this is a danger to the public".
"I do not think Tom had a chance to defend himself, or react in any way."
Mr Brown, who worked at the BBC's information and archives section, left a house in Mayfair Terrace, Southgate, at 0300 BST, after a night with friends.
A passer-by found his body an hour and a half later in Southgate High Street, called an ambulance and waited for paramedics to arrive. Police want him to get in touch.
In a statement, Mr Brown's family described him as a "decent, pleasant and caring man".
"Tom was the baby of the family and his senseless death has left his parents, brothers and sister completely bereft," they said.
"We urge anyone who may have any information, however insignificant, to contact the police. It is vital that Tom's killer is brought to justice so that no other family has to suffer the pain we are enduring."
Colleagues were shocked by Mr Brown's killing, describing him as "an extremely likeable guy". He had hoped to become a cameraman.
He had recently graduated from Southampton University with a politics degree and would have celebrated his 28th birthday on Sunday.
Det Ch Insp Garnish added: "We believe it was a totally unprovoked, violent and forceful attack on a man walking home after an enjoyable evening out with his friends and very near his home.
"Tom was nothing other than a loving member of his family and liked by
everyone. He was not involved in any conflict of any sort."
Police have begun a murder investigation and want anyone who saw Mr Brown, who was wearing a blue zip-up top, black trainers and glasses, to contact them.
Up to 40 police officers are conducting house-to-house inquiries.