A shelf-stacker took a woman captive and brutally raped her three times in a terrifying 90-minute ordeal as she walked home from a Christmas party.

Angelo Bock, 23, an immigrant from Namibia, has been told he faces a "substantial" time in prison after subjecting the 27-year-old to the horrific ordeal in the early hours after Boxing Day last year.

The supermarket worker also frog-marched his victim through the streets near Bradford University and tried to force her to get money out of a cash machine.

When that failed, he beat her head against the hole-in-the-wall machine, leaving her bruised and battered.

She only escaped from Bock's clutches when she fled towards three passing men, who chased after him down an alleyway, but lost sight of him.

Bock was caught because he had made phone calls to his family in Africa using his victim's mobile phone which allowed police to trace him.

Yesterday, at Bradford Crown Court, Bock pleaded guilty to three counts of rape, false imprisonment, sexual assault, robbery and attempted robbery.

Judge Linda Sutcliffe, adjourning sentence for psychiatric reports, told Bock his sentence "will, in any event, be a substantial custodial sentence."

The court heard how the woman, who cannot be identified for legal reasons, was walking in the Great Horton Road area of the city, near the junction with Claremont, after a Boxing Day night out with friends.

Just after 1am on December 27, she texted her boyfriend to say she had become lost looking for a taxi rank and he left the nightclub to try to find her.

But minutes later, the woman was grabbed by 23-year-old Bock and subjected to a horrific 90-minute ordeal.

He forced her to a nearby car park, and assaulted her, before marching her down Claremont, turning right at the junction with Easby Road and cutting into the grounds of the University of Bradford. He took her to a football pitch off Trinity Road and raped her again.

He later tried to get her to withdraw money from a cash machine in Mannville Terrace, frog-marching the terrified woman to a machine in Mannville Terrace, which was captured on CCTV.

When he was unable to get any cash he banged her head against the machine.

The woman, bruised and distressed, escaped when she ran in terror to three men passing by. Two of them chased the suspect down an alleyway but lost sight of him.

Today the head of the investigation, Detective Inspector John Armitage, said the victim was still devastated and unable to go out alone.

"Events were out of her control for over an hour. It was a horrible experience," he said.

Police launched an intensive hunt for the attacker and trawled through hours of CCTV footage looking for clues.

They also issued an e-fit of the suspect and Bock was arrested about a month later.

DI Armitage, from Bradford South CID revealed how "painstaking and excellent detective work" tracking down mobile phone numbers between the UK and Africa led to his arrest.

Within an hour of the attacks, the supermarket shelf stacker had phoned numbers from the victim's mobile to his home country of Namibia.

They were traced by police but the people who had received the calls denied they had been contacted.

Nut Namibian police then tracked numbers dialled to the UK from there.

One was to an address in Kent where inquiries led them to Bock's address in Bradford.

DI Armitage, said the co-operation with the Namibian police, coupled with the accuracy of the victim's e-fit, combined to lead to the arrest.

He said: "The victim had made such a good effort to describe him it was nearly as good as a passport photo. I have never seen one as close.

"It was good, international police co-operation."

Bock, a fair-skinned Namibian, had been on a three-year work permit.

He initially denied the offences but admitted them after 43 minutes under interview.

Yesterday, he pleaded guilty to charges of false imprisonment, sexual assault and three offences of rape. Bock, of St Blaize Court, Manchester Road, Bradford, also admitted a robbery charge relating to his victim's mobile phone and an attempted robbery matter following the failed attempt to get money from the cash machine.

His barrister, Tahir Khan, told the court: "Angelo Bock admitted these serious matters when he was interviewed by the police and has pleaded guilty to the indictment at really the first opportunity.

"There was never going to be any suggestion of him not accepting that he was responsible for these offences.

"He understands that he is going to receive a long prison sentence."

Bock, who showed no emotion throughout the hearing, was remanded back into custody to await his sentence, which is expected to take place on May 27.