The most prolific rapist in British legal history has been given multiple life sentences, after a 10-year campaign of sexual violence involving 190 victims.

Reynhard Sinaga (36) was found guilty of rape and sexual assaults against 48 men.

But police believe Sinaga, originally from Indonesia, may have assaulted many more - potentially upwards of 190, 79 of whom they have not yet been able to identify.

Ian Rushton, deputy chief crown prosecutor, said: "Reynhard Sinaga is the most prolific rapist in British legal history.

"His extreme sense of sexual entitlement almost defies belief and he would no doubt still be adding to his staggering tally had he not been caught."

Sinaga arrived in Britain in 2007 to study a master's degree at Manchester University, and then a PHD in human geography at Leeds University.

He lived alone in a flat in the centre of Manchester, in an area busy with pubs and clubs frequented by students, becoming what the prosecution service there described as a "strategically located" base for his offending.

CCTV footage showed Sinaga preparing for an attack in May 2017, leaving his flat around 1.00am and walking through the streets around his home before finding a victim.

Sinaga would prey upon men who were young, drunk and alone.

A general view of the night club 'The Factory' in Manchester, where Reynhard Sinaga watched and picked up men that he later raped | Image: Peter Byrne/PA Wire/PA Image

Mr Rushton said: "Most of the victims were taken in by Sinaga's friendly approach to them. He doesn't look violent or predatory.

"He offered them a drink, or a place to charge a mobile phone up in his nearby flat. Within minutes of them entering his premises, they'd been drugged, absolutely overpowered by the drug that he administered.

"And on occasions he's repeatedly violated them through the night, recording everything on his phone for his own gratification."

All but a few of Sinaga's victims were white, heterosexual men. The average age was 21.

"Reynhard Sinaga is a depraved offender, a sexual offender who has, we believe, offended in Manchester for over 10 years," Greater Manchester Police Assistant Chief Constable Mabs Hussain said.

"He has taken advantage of young men in the city centre, who came to our vibrant and safe city for a night out with their friends."

Mr Hussain added: "Some of them may know that they have been a victim of a crime, some of them may not. We don't want to traumatise them but what we want to do is try and offer any support that we can."

Police believe that Sinaga gave his victims a drink laced with gamma hydroxybutyrate, also known as GHB or the "date-rape drug".

Because of the nature of the drug, the majority of victims had memory loss and had no idea that they had been raped.

Reynhard Sinaga is seen on CCTV in the hallway outside his apartment | Image: IRN/Sky News

Victims' statements reveal that many victims only found out they had been raped when the police contacted them.

Many described feeling alienated from close family and friends and have suffered lasting psychological trauma as a result of what happened to them.

One victim said Sinaga could not have hurt him more if he had stabbed him.

He added: "Sinaga robbed me of all my future... all I did was drink to numb the pain."

One victim said: "I did not know why they needed to see me but I was absolutely devastated to hear that I had been a victim of rape, after being drugged, and this sexual act was filmed by a man, I now know to be Sinaga."

Another victim, aged 20, who was raped five times said: "Nothing prepared me for what the police told me. I was in complete shock. I knew I could never tell my parents."

He added that he ended his relationship with his girlfriend and shut himself off from his friends, adding: "He trashed my life for his own selfish acts."

Another victim said: "I felt numb; I was totally shocked, embarrassed, betrayed and very angry. His actions were disgusting, unforgivable."

And another wrote: "I wish the worst for him, I want him to feel the pain and suffering I have felt. He has destroyed a part of my life."

Sinaga's offending was eventually discovered in June 2017 when a victim woke up mid-attack and called the police.

Officers who searched his flat found days' worth of footage that Sinaga had recorded of him carrying out the attacks.

The court heard how Sinaga routinely copied his victims' Facebook profiles and stole their photos.

The prosecution said there was evidence he was collating or cataloguing his victims.

Over the past two years, there have been four criminal trials at Manchester Crown Court, involving nearly 160 counts of rape and sexual assault against 48 men.

Sinaga pleaded not guilty throughout, claiming the attacks were consensual.

Inside Reynhard Sinaga's apartment | Image: IRN/SkyNews

As part of a defence that was dismissed by prosecutor Iain Simkin as "ludicrous", Sinaga told jurors he had sex with strangers on the floor of his flat because he did not want to "make a mess of my bed".

He claimed the complainants approached him in the street before they went to his apartment, where they agreed to indulge his fantasy of sexual activity while they pretended to be dead.

Sinaga was found guilty on every count of rape and sexual assault he was accused of.

It is only now, after the conclusion of the trials, that reporting on the story has been allowed.

Sinaga was already handed two life sentences after the first three trials.

The same sentence - with a minimum term of 30 years - was handed down on Monday.

Sentencing, Judge Suzanne Goddard told Sinaga: "You are an evil serial sexual predator who has preyed upon young men who came into the city centre wanting nothing more than a good night-out with their friends.

"One of your victims described you as a monster. The scale and enormity of your offending confirms this as an accurate description."

The judge accused Sinaga of showing "not one jot of remorse" for his actions, and noted that he "seemed to be enjoying the trial process".

She praised the "extreme bravery" of the victims who had come forward, who she said were understandably "deeply traumatised" by what had happened to them.