A Black Lives Matter protest has been staged in Liverpool following the death of an 18-year-old black teenager while in police custody.

On Saturday, some three hundred people took to the streets of Liverpool to protest against the death of Mzee Mohammed while in the custody of Merseyside Police, under the banner of Black Lives Matter.

Marching behind his sister Melissa and their mother, Karla, from the train station to the shopping centre where Mzee was detained, the crowd chanted “Justice for Mzee”.

Addressing the crowd, Karla said: “I want to ask the Lord to see justice for my son,” the Guardian has reported.

She added: “I will not rest, I will walk in my son’s shoes until I get answers, and anyone who had a hand in my boy’s death will be brought to justice.

“My son will not be a number or a statistic. His death will not be in vain.”

A video posted by Emma Jane (@thelingerieblog) on Jul 16, 2016 at 8:59am PDT

The procession then continued to march to the sound of the crowd chanting: “Black Lives Matter, Mzee’s Life Mattered.”

A similar protest in Mzee’s name was held in London on Sunday.

Three days earlier, police officers had been called to the Liverpool One shopping centre following unconfirmed reports that a black teenager was acting in an “aggressive and erratic” manner and carrying a knife.

According to the police, the teenager, later named as Mzee Mohammed, was being detained by the shopping centre’s security staff when they arrived but suffered “a medical episode” at about 6.30pm, while in the custody of police at the scene.

Merseyside Police say Mzee was officially pronounced dead at 7.53pm on Wednesday after being taken to the Royal Liverpool University Hospital.

But his family have disputed that version of events, releasing a five-minute video to the press which shows Mzee lying unconscious and bare-footed on the floor while still handcuffed. The family insist that Mzee was already dead when the video was taken.

His sister, Melissa, told the Liverpool Echo: “No attempts were made to resuscitate my brother, to check his pulse, and there was no sheet or blanket covering his body.

“Seeing this has made us distraught.

“Police told us that when Mzee became poorly they took his handcuffs off him, but you can clearly see he’s put on the stretcher in handcuffs.

“This is the case of an 18-year-old boy who died on his own, in town, on the pavement.”

She added that when the family had been allowed to see the body on Thursday evening, there were dark bruises around Mzee’s ankles from being lifted onto a stretcher.

The family’s version of events is being disputed by Merseyside Police and the Northwest Ambulance Service, whose paramedics attended Mzee. They say he was still alive when taken to hospital, and was being treated properly.

“Based on that video, we have no concerns about the treatment given to this patient at that time,” a spokesman for the Ambulance Service said.

As is standard in all cases in which a person dies after contact with police, the Independent Police Complaints Commission (IPCC) has launched an investigation into Mzee’s death.

In a statement released on Thursday the IPCC said: “Officers were called to an incident at the shopping centre at about 6.30pm yesterday evening. The man subsequently became unwell and was taken by ambulance to a local hospital where he later died. IPCC investigators were deployed following notification of the incident and have been overseeing examination of the scene and the post-incident procedure.”

A post mortem examination on Friday proved inconclusive, but further tests, including toxicology checks, will now be carried out in the hope of determining a cause of death.

However, as the Black Lives Matter movement takes on a life of its own in the UK and elsewhere the outcome of the IPCC investigation may prove insignificant.

We are starting #NUSNEC with a moment silence in memory of Mzee Mohammed, a student who last week died in police custody. #BlackLivesMatter — Sorana Vieru (@SoranaBanana) July 18, 2016

A Black Lives Matter march in Derby attracted around 100 protestors, with locals saying they were coming out to protest against the heavy-handed way in which British authorities deal with black citizens.

Davinia Harmer, 34, told the Derby Telegraph: “I have been outraged by what had happened in the U.S. Events like this should happen in every city in the UK because, although we don’t have gun problems, the police are too heavy handed with the black community. It’s outrageous.”

And Calvin Forest, 48, said he had chosen to attend the event as he was “disgusted” with what happened in the U.S.

“The only way to solve this problem is to disarm the police in the country,” he said “It’s a horrendous problem out there. I’m shocked and outraged with what’s happened. Today’s event is so important to get the message out there that it is wrong.”

#BlackLivesMatter #MzeeMohammed should not have been added to this list. just watched him die. stop killing us! pic.twitter.com/xdCFVs9Hbv — TheRzabeth I (@HowAboutBeth) July 14, 2016

The events follow a three day protest staged outside the U.S. Embassy in London last week, while Birmingham, Manchester, and Leeds have also played host to large protests.