A mature student labelled the UK’s most prolific ever rapist could have his time in prison increased after the attorney general’s office confirmed it was to review whether his sentence had been unduly lenient.

Reynhard Sinaga was jailed for life but given permission to apply for parole after 30 years following four separate trials in which he was found guilty of drugging, rendering unconscious and sexually abusing 48 men in Manchester.

Now, the sentence will be reconsidered after a letter was sent to the office of Geoffrey Cox officially requesting the 36-year-old Indonesian national be prevented from ever walking free.

If a full life sentence was imposed, it would be the first time in British legal history that such a punishment had been handed down to someone who had not committed murder.

“The case has been referred to our office and is now under review,” a spokesperson told The Independent.

Reynhard Sinaga: Most prolific rapist in UK history jailed Show all 11 1 /11 Reynhard Sinaga: Most prolific rapist in UK history jailed Reynhard Sinaga: Most prolific rapist in UK history jailed Reynhard Sinaga was jailed at Manchester Crown Court for life and must serve a minimum of 30 years after he was convicted of offences against 48 men Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed The bedroom floor, where dozens of rapes took place, in the the home of Reynhard Sinaga Sinaga, who was convicted on 159 sexual offences including 136 counts of rape in Manchester between January 2015 and May 2017, drugged 48 men and filmed himself sexually violating them while they were unconscious in his city centre apartmen Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed A general view of the night club Fifth in Manchester where Reynhard Sinaga watched and picked up men that he later raped Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed CCTV grab of Reynhard Sinaga on Princess Street The Indonesian student posed as a good samaritan, offering the men a place to sleep or more drink, the court heard Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed Reynhard Sinaga, middle, appearing in the dock at Manchester Crown Court on the day he was charged Julia Quenzler /SWNS.COM Reynhard Sinaga: Most prolific rapist in UK history jailed A general view of the apartment Montana House next to the night club The Factory Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed The living room at the home of Reynhard Sinaga His victims – who were mostly heterosexual – had little or no memory of the assaults, which Sinaga filmed on his mobile phone. The men left the flat unaware they had been violated. Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed The iPhone 4 taken by a victim and used to convict Reynhard Sinaga Sinaga was caught after one of the men regained consciousness and fought him off, before taking his phone to the police Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed Bottles of alcohol which were used to spike victims in the home of Reynhard Sinaga Sinaga is thought to have laced alcoholic drinks with a drug such as GHB, known as liquid ecstasy, to incapacitate his victims Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed Greater Manchester Police has urged anyone who believes Sinaga may have approached them on a night out to come forward. Officers say he may have been committing crimes for 10 years Greater Manchester Police/PA Reynhard Sinaga: Most prolific rapist in UK history jailed Mobile phones found in the home of Reynhard Sinaga When Greater Manchester Police examined the attacker’s multiple digital devices, they found 3.29 terabytes of graphic material – the equivalent of 250 DVDs – depicting sexual assaults. Jurors who had to watch some of the mobile phone footage were later offered counselling Greater Manchester Police/PA

Under the unduly lenient sentence scheme, a decision will be made within 28 days.

It is not clear who sent the letter requesting the review but, at Sinaga’s trial, the Crown Prosecution Service was keen to push for a full life term. Anyone can send such a letter to the attorney generals’ office as part of the unduly lenient sentence scheme, including victims or their relative.

It is understood that key points it raises are the fact that, while Sinaga was found guilty of crimes against 48 men, Greater Manchester Police have video evidence that the real number of victims is at least 195 – many of them unidentified.

An incident room set up after the rapist’s identity was made public on 6 January has received “numerous” calls from potential victims, a force spokesperson has said.

At his initial sentencing at Manchester Crown Court, Judge Suzanne Goddard told him it was “borderline” whether he should be given a whole-life term but decided that he could be considered for release when he was 66.

“Whilst these offences collectively and individually are of the utmost seriousness, and in my view did involve a risk to life … the features of torture and violence are absent, and do not involve death or lasting serious physical injury,” she said. “You are clearly well versed in the necessary doses and mercifully none of the victims suffered any lasting serious physical effects.

“The sole feature that would allow the court to contemplate the passing of a whole life order would be the vast scale of your offending which now involves 48 victims. This is in my view a borderline case, as described in the authorities, and as such I must therefore shrink back from passing a whole life order.”

Sinaga targeted men – often teenagers – who had been separated from friends while enjoying nights out in Manchester city centre.