The family of a man shot dead by police have called for a homicide investigation as it was revealed that a search of the scene had found no gun linked to the 24-year-old. The family of Chris Kaba called for “answers and accountability” from the Independent Office for Police Conduct (IOPC), which is investigating the shooting on Monday night in Streatham, south London, amid claims that the watchdog’s investigation is being mishandled. Kaba was driving a car which was first rammed before being boxed in by police. He was killed by a single shot that entered through the driver’s side of the windscreen of the Audi. The IOPC said the car Kaba was in had triggered an intelligence system indicating it was linked to a firearms incident days earlier, which led police to chase and then force the vehicle to stop. A detailed search has been completed and “no non-police issue firearm has been recovered from the vehicle or the scene”, the IOPC said on Wednesday night. The Guardian understands that the Met is monitoring community tensions in the area, and that IOPC investigators do not believe there is any indication of wrongdoing by the officers involved – who are being treated as witnesses. In its statement, the IOPC gave new details about the lead-up to the shooting: “Police officers in an armed response vehicle attempted to stop the vehicle Mr Kaba was in, after the activation of an automatic number plate recognition camera which indicated the vehicle was linked to a firearms incident in the previous days.” In a statement, Kaba’s family demanded that officers should be placed under criminal investigation by the IOPC: “The family of Chris Kaba seek a homicide investigation into his death from the outset. “We have today told the IOPC of that demand and that we do not want any delay as has happened in other fatal shootings – otherwise we and the wider public can have no confidence that the police will be held to account. “We are devastated; we need answers and we need accountability. We are worried that if Chris had not been Black, he would have been arrested on Monday evening and not had his life cut short.” Deborah Coles, the executive director of Inquest, said a criminal inquiry was needed: “It is essential that fatal use of force by police is examined with this high level of scrutiny.” Police officers need to have a reasonable and honest belief that their or others’ lives are in danger before they open fire. The force they use must be proportionate, and they do not need to be right about the threat they perceive. The IOPC is investigating who the car belonged to and what officers knew about its ownership and possible occupant at the time. Kaba’s family, and the officers involved, face a wait for the results of the investigation and then an inquest into the death. The shooting happened in an area of London where trust in the Met has plummeted, and there was anger and concern at the shooting on Wednesday, as well as sadness at Kaba’s death. The IOPC’s regional director, Sal Naseem, said: “We recognise that there is community concern following this incident … We are working hard to piece together all of the circumstances and we want to reassure the community that these questions will be answered in due course. “While we have already undertaken some door-to-door inquiries in the neighbourhood, there is likely to be members of the public we are yet to speak to which may have information that could assist our investigation.” On Wednesday, family and friends paid tribute to the “kind” and “happy” 24-year-old. Kim Alleyne, 49, whose daughter Karimah Waite was engaged to Kaba, said: “He was so loved. He was so funny. He was super-kind. Crazy. He was always happy. He would do anything for you.” She added: “He was a fiance, he was due to get married in five months’ time. He’s got a baby on the way that he’s never going to see. It’s horrible and so shocking and so sad.” Jefferson Bosela, 27, Kaba’s cousin, said: “He was a good person, a good, happy guy. He didn’t deserve that. No one deserves that. Nobody deserves to be shot by the police, whether they are a good person or a bad person.” Once the IOPC starts an investigation, the force being investigated is limited in what it can say. The Met’s commander, Alexis Boon, expressed sympathy to Kaba’s family for the “devastating and lasting impact this tragic incident will have on them”. He added: “I understand that this incident is extremely concerning and I would like to reassure the community that the Met is cooperating fully with the Independent Office for Police Conduct. “I also recognise that the family and community want answers about what happened. I know the IOPC investigators are working hard to establish the facts, but also need some time and space to be able to progress their inquiries.”