A Metropolitan police officer who put a Taser to the neck of an innocent black child after he had been forced to kneel in the street has been found guilty of gross misconduct but allowed to keep his job.

Jamar Powell told the Guardian he had feared he might die during the incident in September 2020, was left traumatised and would struggle to ever trust the police again, having been stopped and searched more than 30 times with nothing ever being found.

A disciplinary panel concluded on Friday that it did not believe PC Connor Jones’s claim that he had not pressed the stun gun to the neck of Powell, who was 16 at the time.

The incident happened during a stop and search in Greenwich, south-east London, when police said they were hunting for a man armed with a samurai sword and wearing an “all black tracksuit with hood”.

Powell was not wearing dark clothing, nor a hood, but some of his friends were. As well as officers with Tasers, armed officers with guns surrounded Powell. Police claimed the teenager had walked away, which heightened their fears.

He had been walking at about 11pm with one white and three black friends, all of whom were let go after being searched.

One friend filmed the incident on his camera phone, which proved crucial as Jones did not activate his body-worn video camera and footage from a colleague’s camera could not be provided by the Met.

Originally the Met had investigated the incident and cleared officers of any wrongdoing. The Independent Office for Police Conduct said the force had disagreed that the officer had a case to answer for gross misconduct, even after the watchdog had conducted its own investigation.

On Friday, the disciplinary panel cleared Jones of discrimination but gave him a final written warning, which stays in force for three years.

Powell, who is now 20 and works for a charity, told the Guardian the officer should have been sacked and said his experience showed the Met had not changed.

“It is still with me, it will be with me for the rest of my life,” Powell, now 20, said of the incident. “I was traumatised that day. I will never see the police in the same light, the lack of respect, despite being a law-abiding citizen.”

Powell said the punishment from the panel was a mere “slap on the wrist” and added: “As an officer, if you lose control of yourself on a child, you should not have the opportunity to do the same thing again and cause trauma.”

He said he still believed racial discrimination explained his treatment and that a dismissal would have sent a message to other officers.

The IOPC regional director, Mel Palmer, said: “There was no need for the Taser to be placed on Jamar’s neck to handcuff him when he was already kneeling in the road, with his hands clearly visible and placed on his head.

“This would no doubt have been a frightening experience for Jamar, with officers armed with firearms and Tasers, and PC Jones’s behaviour was oppressive and bullying.

“He denied pressing his Taser against Jamar’s neck, however, after hearing the evidence, the panel found that he did what was alleged and that this use of force was not justified, proportionate or necessary.”

Last August the Guardian revealed the Met had paid damages to Powell and apologised.

Ch Supt Trevor Lawry, the head of policing in south-east London, said: “We acknowledge that this was a distressing incident for the boy involved and recognise the ongoing impact it has had on both him and his family. We have previously apologised for the trauma caused and we repeat this again today.

“It is right that any use of force and stop and search are scrutinised, and in this case the panel found that PC Jones’s actions were not proportionate or necessary.”

The Met is expected to soon launch a race action plan to try to fix a lack of trust in it from minority ethnic communities.