The family of a young surveyor stabbed in a "callous" attack by a gang of robbers as he walked home have been left distraught after he died in hospital.
Paul Tanner, aged 22, was ambushed by three teenagers in an attempted robbery as he walked across St Paul's Square in Birmingham city centre after a night out with friends.
Police said the youths were looking for someone to rob and that Mr Tanner and a friend had been in the wrong place at the wrong time.
The killers showed their victim no mercy as a knife was plunged into his chest just yards from his luxury flat in the Hockley area of the city.
Police said it was not yet clear whether anything had been stolen during the incident or whether the two men stood up to their assailants before the 22-year-old was fatally wounded.
His friend was left traumatised by the unprovoked attack, which happened in the early hours of Friday morning, but was not injured and managed to call police.
Detectives launched a murder inquiry after the victim died at about 9.30pm on Friday in hospital with his family at his bedside.
Chief Superintendent Peter Goodman, of West Midlands Police, said: "This was a callous act of gratuitous violence carried out by a ruthless group of individuals who we are determined to bring to justice."
The two men were walking across St Paul's Square as a short cut on their way home after a night out when they were attacked by the three would-be muggers.
One of the gang produced a knife during the scuffle that followed and plunged it into Mr Tanner's chest.
Ch Supt Goodman, speaking from the scene of the murder, said: "They had been out socialising for a drink with friends locally and they were on their way back from that.
"They were using the churchyard as a short cut and they were approached by this group of individuals. There was an attempt made to rob them and the robbery went wrong and some sort of knife or sharp instrument was used.
"The level of violence used was clearly gratuitous and disproportionate.
"It is a very, very safe area, quite an affluent area where crime is generally very low and we are equally surprised that something like this has happened here.
"I think they happened to be in the wrong place at the wrong time. This group was clearly out looking for somebody to rob at this time.
"This was a vicious, callous and unnecessary attack - an awful, awful tragedy.
"The offenders are young men between 16 and 18 and they have probably gone back to families after they have done this.
" Somebody somewhere knows who has committed these offences.
"This is a murder inquiry for a very callous offence so if you do know anything at all, please come forward.
"We are absolutely determined that we will bring these offenders to justice at the first opportunity."
A police spokesman said Mr Tanner's family were too upset to talk about the tragedy and wished to be left alone to come to terms with their ordeal.
The area around the church, which is in a square near Birmingham's Jewellery Quarter and is surrounded by restaurants, bars and apartments, was sealed off for forensic examination over the weekend.
Mr Tanner was just yards from his home on Northwood Street - an area of newly converted flats populated by young professionals living in Birmingham - when he was killed.
The first attacker was described as a mixed-race youth, aged around 17, of chubby build with a chubby face and short Afro hair, wearing light grey tracksuit bottoms, a light top, black cap and white trainers.
The second youth was described as black, possibly of Caribbean origin, aged around 16 and 5ft 7in to 5ft 8in tall, of slight build, wearing a black cap, black tracksuit and hooded top. The third youth was believed to be of mixed race and aged around 16 or 17.