In an update on Thursday, detective chief inspector Dave Higham, from Kent Police, said: "We have carried out a full and extensive investigation into Lisa's tragic murder and our enquiries have concluded that the suspect is believed to have died after falling into the River Thames.
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"Multiple searches of several areas of the river have since been assisted by the Metropolitan Police, London Fire Brigade and Coastguard, but at this stage we have not recovered a body.
The suspect in the fatal shooting of a woman outside a pub in Kent is believed to be dead, police have said.
Police say a handgun was found inside the vehicle, and enquiries have since established that the suspect entered the water below.
