Dramatic footage shows a police officer pepper spraying a serial robber as he dangles from a tower block drainpipe 100 feet from the ground.
PC Luke Wenham, 31, blasted Carl Cumberbatch twice as he tried to escape at Albert Barnes House in South London.
Cumberbatch momentarily lost his footing and was temporarily blinded, clinging to the drainpipe with one hand.
PC Wenham's career is now in ruins after he was convicted of two counts of common assault at Westminster Magistrates' Court.
The officer sobbed as District Judge Louisa Ciecióra told him there was an "obvious risk" of Cumberbatch falling to his death.
The footage released by watchdog the Independent Office for Police Conduct (IOPC) shows PC Wenham using the spray twice as Cumberbatch, wanted for several robberies, clambers down the side of the building.
When police arrived at the 12th floor flat Cumberbatch barricaded his door with furniture and officers had to force entry on August 17 last year.
Cumberbatch then dashed to the window and scrambled down the drainpipe.
"It was between the 12th and 10th floors that PC Wenham sprayed Mr Cumberbatch with irritant spray from the window of flat 73," said Tom Broomfield, prosecuting.
"A member of the public filmed what was happening. It clearly shows PC Wenham calling Mr Cumberbatch's name...while he is on the side of the building holding on to the pipe.
"In response Mr Cumberbatch looked up to where PC Wenham was calling from and then PC Wenham deployed the spray in the direction of Mr Cumberbatch whilst Mr Cumberbatch had hold of the pipe with only one hand.
"That appeared to result in Mr Cumberbatch momentarily losing his footing.
"At least one of Mr Cumberbatch's feet appears to lose contact with the pipe after spray had been deployed."
After he was sprayed the first time, Mr Cumberbatch continued to shimmy down the pipe to a flat on the eighth floor.
PC Wenham then sprayed the suspect again from another bottle.
Cumberbatch managed to climb down onto the balcony of flat 44 on the sixth floor.
PC Wenham and his colleagues then began a "very lengthy discussion of negotiation" with Mr Cumberbatch as he repeatedly threatened to leap to his death.
Cumberbatch was finally arrested later that afternoon.
In a statement read to the court Cumberbatch said he was climbing down the pipe when he heard someone call his name and he naturally looked up.
"I heard someone shout 'Carl' and it's a natural instinct to look up, and I got sprayed in the face with 'CS' gas. I've been sprayed with 'CS' in the past, that's how I know.
"It was hard to hold on, if I let go, I would fall off...I was unarmed and I think it was wrong for the police to do that...I think only the adrenaline kept me holding onto the pole.
"I couldn't see anything; I couldn't see my foot or anywhere I could go...I put my head down because it was burning, and it hurt. The officer kept spraying onto the top of my head."
Cumberbatch was later convicted of 11 charges of robbery, two of criminal damage and two counts of racially aggravated public order.
PC Wenham told the court it was a "high risk situation" and that he believed his use of pepper spray was 'completely reasonable' in order to avoid risk to the wider public.
He said his main concern was to save the residents of the block of flats from the potential harm Cumberbatch presented due to his history of violent offending.
"I was just concerned for occupants in that address and anyone in the stairwell, anyone off to work and children off to school, I believed he was going to do anything he could to avoid capture," he said.
PC Wenham, from Dartford, Kent, denied but was convicted of two counts of common assault after a one-day trial.
Judge Ciecióra told the court: "Mr Cumberbatch was obviously, from his history, a violent offender, he was known to evade officers and known to use force.
"He was willing to climb down a pipe of unknown quality at a significant height to not be arrested.
"For both offences you acknowledge there was an obvious risk of Mr Cumberbatch falling.
"And you admit its not disputed the spray causes certain reactions; involuntary spasms, legs to become weak, tense muscles and so on, and you admit those were possible reactions.
"You admit you aimed the spray intending to cause the reactions known to be caused by the spray. I could not accept your account you used the spray as a distraction to cause Mr Cumberbatch to move onto the balcony and be inconvenienced by the spray.
"I am sure you are aware it would not simply cause an inconvenience... and you would be aware it would include the risk of death.
"For both incidents it cannot be said the use of force was reasonable, proportionate or necessary, I therefore find you guilty of both offences."
PC Wenham, who wept as he was convicted, will return to Westminster Magistrates Court for sentence on July 26.
Detective Chief Superintendent Seb Adjei-Addoh, in charge of policing Southwark and Lambeth, said: "Officers know that their actions will be held to account and where any use of force is deployed, must always consider whether it was necessary and proportionate to the circumstances.
"It is clear in this case that not only was PC Wenham's response completely disproportionate to the situation he faced but also, by doing what he did, he put a member of public at risk of harm.
"PC Wenham has let down not only himself but many hardworking police colleagues who strive to improve trust and confidence with our communities.
"I am pleased that this matter was put before a jury to make a decision following a careful consideration of all the facts."
IOPC director Steve Noonan said: "At the time he was sprayed, the man was not posing an immediate risk to the officers or anyone else.
"It is clear that in spraying the man twice at considerable heights, PC Wenham exposed him to the genuine risk he may have lost his grip on the pipe and fallen, which would have likely had fatal consequences."
