Mark Blanco fell to his death after a fight with Pete Doherty. His mum is certain it wasn't accidental.

In 2006, aspiring actor Mark Blanco was found dying on the pavement outside a block of flats in London.

He had fallen from a balcony in an apparent accident following an altercation with British musician Pete Doherty. But his mother Sheila Blanco believes he was killed, and she's spent the past 17 years trying to prove it.

On the night of his death, Blanco had attended a party at the home of Paul Roundhill, Doherty's literary agent, in Whitechapel, London. He got into an altercation with Doherty, The Libertines frontman and former fiance of Kate Moss, after asking the musician to come watch him perform in a production of Dario Fo's Accidental Death of an Anarchist - a play about a man who falls to his death from a window.

Those present at the party, including Doherty and Roundhill, have always denied responsibility for Blanco's death. 

New British TV documentary Pete Doherty, Who Killed My Son? has gone deep on the Blanco case and his mother's 17-year quest for justice, airing interviews with those at the gathering as well as CCTV footage to paint a picture of the 30-year-old's final moments.

Naomi Stirk, a woman at the party, recalled Blanco 'pinning' Docherty to a wall, enthusiastically encouraging him to see his play.

"Peter was motioning with his eyes to Johnny ['Headlock' Jeannevol, Doherty's minder] and [Roundhill] in a way that they would understand to say, 'Help me out here,' so they physically escorted Mark out of the flat. The atmosphere was sinister," she said.

Roundhill had previously admitted to evicting Blanco out of the flat, setting fire to his hat and punching him in the face three times.

Blanco returned inside shortly after being kicked out and was later found unconscious and covered in blood on the footpath outside. He was pronounced dead on December 3, 2006 at the Royal London Hospital. Scotland Yard's findings indicated Blanco had severe head injuries consistent with a fall.

"I was the last person to say goodbye. I put my head on his chest and I just promised I would find out what happened," Sheila, Blanco's mother, recalled in Pete Doherty, Who Killed My Son?

No charges have ever been laid in relationship to Blanco's death

Stirk recalled holding Blanco's hand after he was discovered by another guest, Annabel.

"I remember just holding his hand and just trying to make sure he was comfortable because he was dying," she said in the documentary.

"You feel terribly helpless, of course, because there's nothing that you can do... I know that something horrid went on and it wasn't accidental."

The documentary shows how analysis commissioned by the BBC in 2012 claimed that vital information had been missed on the CCTV footage.

Doherty, circled, fleeing the scene. Image: Sky News.

It features FBI instructor Grant Frederick, who reviewed footage of the night, including Blanco falling from the balcony and Doherty, Headlock and Groundhill leaving the flat, stepping over his body, and running away.

Frederick said, after using a technique called 3D reverse project, the footage strongly indicated at least one other person was on the balcony with Blanco when he went over the edge.

"What I would say is that Mark has come out and somebody has taken Mark and is putting him over the balcony. If the measurements and the distance are correct, then Mark was thrown over the balcony. Mark was murdered," he explained.

Sheila called the footage "absolutely callous".

"An irreprehensible lack of humanity. He was definitely pushed over, thrown over, but the Metropolitan Police do not wish to uncover what the truth is. It's not the job of a mother to investigate her son’s death."

In testimony at the coroner's court, Headlock — Doherty's bodyguard at the time — said he had confessed to police while drunk and high on cocaine that he had pushed Blanco to his death, but later retracted and was released without charge.

In a statement given to Channel 4, Roundhill said Blanco was his good friend.

"I would not protect anyone who had a part in his death. I attempted to steer Pete Doherty away from drugs… My sympathy and support is for Sheila Blanco. Mark and his family deserve justice."

Doherty also shared a statement.

"I am sorry for Mrs Blanco's loss and I welcome any assistance people can give her to come to terms with what happened," he said.

Feature image: Getty/Channel 4.