London - A graduate student from Indonesia living in Manchester, England, was sentenced Monday to life in prison for raping or sexually assaulting 48 men.
Reynhard Sinaga, 36, met his inebriated victims outside of nightclubs and lured them back to his apartment, where he drugged and attacked them, filming the assaults on his cellphones.
A crown prosecutor called him the "most prolific rapist in British legal history."
Sinaga's identity and details of his crimes had not been revealed before Monday, as the courts had ordered a two-year-long media blackout, until the end of his fourth criminal trial.
Police suspect Sinaga attacked as many as 195 men over several years. Through his multiple trials, he was found guilty, in total, of 159 sexual offenses, including 136 rapes.
The case led to the largest ever rape investigation in Britain.
Police are still trying to identify 70 victims who appear in Sinaga's video footage, according to British press reports from the trial.
At the sentencing on Monday, Judge Suzanne Goddard called Sinaga "an evil serial sexual predator who preyed upon young men who came into the city center wanting nothing more than a good night out with their friends.
She said, "One of your victims described you as a monster. The scale and enormity of your offending confirms this as an accurate description."
Sinaga's modus operandi was to meet men leaving nightclubs near his Manchester city center apartment. According to police and court testimony, the assailant targeted young men who were by themselves, usually sick or intoxicated - and then he would play "the good Samaritan" and offer them another drink, a place to sleep or charge their phones, or help calling a taxi.
Police suspect Sinaga used a powerful date rape drug to incapacitate his victims. Many reported waking up disoriented but not realizing they had been assaulted.
Detective Inspector Zed Ali of Greater Manchester Police told the Manchester Evening News that "some of the offenses happened years ago and they were not aware of it."
A last victim in 2017 managed to call police during his assault. That was when police arrested Sinaga, confiscated his phones and discovered the trove of evidence against him.
During his trials, Sinaga denied raping and assaulting the men, saying instead they were willing participants and pretending to be asleep.
Police said Sinaga could have been assaulting men for as long as ten years - and that evidence against him came not only from the video clips on his mobile phones but other "trophies" that he kept, such as ID cards from the victims.
The BBC reported that statements by victims were read in court, with one man saying he felt suicidal after the attack and another hoping that Sinaga "never comes out of prison and he rots in hell."
Sinaga arrived in Britain from Indonesia on a student visa in 2007. According to the Associated Press, Sinaga received two degrees from the University of Manchester and was studying for his PhD at the University of Leeds when he was arrested in 2017. His doctoral thesis, the AP reported, was "Sexuality and everyday transnationalism. South Asian gay and bisexual men in Manchester."
Sinaga must serve at least 30 years of his life sentence.