A man accused of murdering a string of women and dumping their bodies may have killed up to 180 people - escaping detection because the police force turned a blind eye to his crimes because his victims were mainly drug addicts and prostitutes, a documentary claims.

Lonnie Franklin Jr - dubbed the Grim Sleeper because he allegedly had a break between committing multiple murders - is due to go on trial later this year accused of sexually assaulting, murdering and then dumping the bodies of 10 women across Los Angeles over two decades.

But a new documentary by British filmmaker Nick Broomfield suggests Franklin was able to go on killing for so long, and possibly target dozens more victims, because of a police 'blindness' to his victims - which he likes to a 'genocide happening and nobody was talking about it.'

Mr Broomfield claims had the police properly investigated the murders and disappearances of mostly black, female prostitutes and drug addicts lives could have been saved.

He said: 'People didn't know someone was hunting for them.'

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Lonnie Franklin Jr, dubbed the Grim Sleeper, may have murdered up to 180 people as police in LA turned a blind eye because his victims were usually black and with drug problems, a documentary has claimed

Franklin, who worked as a bin man, will go on trial in June for the murders of 10 women, dating back to 1985. Bodies of the women were found dumped in alleyways wrapped in carpets or stuffed into rubbish bins.

However a police search of his home found pictures and videos of 180 women who could all be possible victims. It is feared some may have been dumped in landfill because of Franklin's job as a bin man.

Mr Broomfield said during the time when the crimes were committed, little attention was paid to the disappearance of around 200 women by the police or the media.

'I thought it was just incredible in the middle of LA which is one of the wealthiest cities in the world, within 15 minutes of the Hollywood sign over 200 women had disappeared in a 25 year period,' he said.

He told the Sun: 'It was almost like a genocide happening and nobody was talking about it.'

In his documentary Tales of the Grim Sleeper, Mr Broomfield claimed police didn't warn people there was a killer lurking in the neighbourhood or do anything to alert people living in nearby Hollywood because the victims were often seen as more of a 'nuisance.'

He said Franklin, a father-of-two, was able to go on killing so long because he targeted vulnerable black women, many of whom had become crack and cocaine addicts in the 1980s.

The suspected victims of the Grim Sleeper: Enietra Washington (left) survived an attempted murder and was found in 1988, Alicia Alexander (centre) was found dead in an alley in September 1988, Henrietta Wright (right) died in August 1986 in an alleyway

Valerie McCorvey (left) was found dead in 2003, Lachrica Jefferson (centre) in January 1988 and Bernita Sparks (right) was found dead and dumped in an alleyway in April 1987

Mary Lowe (left) was found in November 1987 - just a few months before Barbara Ware (right) was found

Princess Berthomieux (left) was discovered in an alley in March 2002, and Debra Jackson (right) in 1995

Mr Broomfield added: 'They were just seen as disposable people.

'The police had this term, NHI, which meant no human involved, which they used to call in murders of prostitutes by gang members. They didn’t take it seriously, they didn’t seek evidence. They would often not even use the proper name of the prostitute, just call it in as a “Jane Doe.”

'They just didn't take it seriously. Most of the women were prostitutes and drug addicts and I don't think it helped that the people were black.'

Mr Broomfield said it could not have been an 'accident' that 200 people disappeared or were murdered in the same small area in a 25 year period. He said had the murders been taking place in somewhere like the wealthy district of Beverley Hills then the area would have been closed down, police presence increased and press coverage of the incident.

A search of Franklin's mint green LA home found up to 180 pictures of women, many of whom are missing

Giving one comparison, he said the disappearance of dozens of women was treated very differently from a case in 1988 where a gang had shot students in Westwood - causing the whole city to be shut down.

The documentary maker said he thinks some of the murders could have been avoided had police taken the disappearances and killings more seriously.

He added: 'I definitely think women's lives could have been saved.

'If police had told the public in 1987 when they knew there was a serial killer who had already killed five victims, if they had told the community then I think things could have been very different and a lot of lives saved.

Franklin was arrested in 2010 after DNA evidence was found which appeared to connect the victims

Stills from the documentary show Franklin after he was arrested in July 2010 for the 10 murders

Mr Broomfield, pictured right interviewing a friend of Franklin's, said the documentary took a year and a half

Pam Brooks was interviewed by Broomfield, giving an insight into life in Los Angeles

'People didn't know someone was hunting for them.'

Mr Broomfield said had people been aware there was a danger they would have been more cautious about accepting lifts from people, because some of the victims were not prostitutes or drug addicts but simply those who were waiting for buses late at night.

Mr Broomfield, who spoke to relatives and friends of Franklin to produce the documentary, claims when his son Christopher told him officers were almost 'grateful' that the alleged Grim Sleeper had rid the streets of some of the 'problem' people they had been dealing with on an almost daily basis.

He added that in the one-and-a-half years it took to make the documentary, Franklin was described as a 'loving father' and almost a Robin Hood figure, who would fix people's cars and get cheap washing machines if they needed them.

Earlier this month a mother-of-two, known only by the name 'Mo', revealed she may have been one of Franklin's intended victims as it emerged that her photo was one of the collection found in his home.

Nick Broomfield (left) claims in the documentary that alleged killer Franklin (right) continued with his killing spree for so long because police turned a blind eye to his victims, who were largely black drug addicts

'Mo' claimed she had been forced to pose for a naked picture for Franklin, her then next door neighbour, after the pair went for a drive in his van in 2006. She claimed that Franklin had showed her other pictures of women, some of which were in strange poses who she thought could have been dead, and then asked her to pose naked.

She claims she agreed to the picture after she noticed a gun and knife in his van.

The photo appeared in a collection of images found by the police when Franklin was arrested in 2010.

Mo told ABC7 she believed she could have been killed by Franklin, now 62.

The alleged killer earned the nickname the Grim Sleeper after he allegedly committed murders between 1985 and 1988, taking a 13 year break before he is believed to have resumed in crime spree in 2002.

Mo said she was stunned when she saw her photo on a documentary about her former neighbor

Franklin, dubbed the Grim Sleeper, is to go on trial for 10 murders and one attempted murder in June

Police arrested Franklin in July 2010 after his DNA was connected to more than a dozen crime scenes.

They had linked the crimes, but did not have a suspect until a crime lab computer traced the sample to one of Franklin's family members. Police were able to get samples by using an officer to pose as a busboy at a pizza restaurant, and extract DNA from dishes and cutlery used by Franklin. +

He will go on trial in June, accused of 10 murders and one attempted murder.

Mr Broomfield said Franklin had been popular in the area, according to locals. But they claimed he was often obsessed with crack addicts - becoming popular with women in the 1980s during the crack epidemic which swept Los Angeles.