Clapham chemical attack suspect Abdul Shokoor Ezedi may be dead after going into the River Thames, police say.
The 35-year-old has not been seen since the night of the attack on 31 January, when an alkali substance was thrown over a mother and her two children.
At a press conference on Friday police said their working hypothesis was that he had gone into the water after last being seen at Chelsea Bridge.
No body has been found and officers said one may never be recovered.
At the briefing Metropolitan Police officers said Ezedi could be seen on CCTV “walking with purpose” for four miles to the Thames and said his behaviour changed at Chelsea Bridge.
They said he could be seen to “lean over the railings” of the bridge before CCTV sightings ceased.
Speaking at Scotland Yard, Cmdr Jon Savell said officers had spent the last 24 hours “meticulously” following CCTV and their “main working hypothesis” was that he had gone into the water.
“We have looked at all of the available cameras and angles, and with the assistance of Transport for London and CCTV from buses that were travelling over the bridge at the relevant time and there is no sighting of him coming off the bridge,” he said.
Detective Superintendent Rick Sewart said death was the “most probable outcome” if Ezedi had gone into the water.
From the hundreds of hours of CCTV officers have combed through, it does not look as though Ezedi has been in contact with anyone else, the force said.
The search for Abdul Shakoor Ezedi, wanted over a chemical attack in Clapham.
The most recent sighting of him remains an image captured on CCTV at about 23:27 GMT on 31 January, crossing Chelsea Bridge.
Cmdr Savell said the forces’ marine support unit would be searching the river but said experts had warned that if someone had gone into the river it might take some time for them to surface.
He added that police had spoken to a member of Ezedi’s family to “break that news”.
A manhunt had been ongoing for more than a week, with police raids carried out in the Newcastle area at properties linked to Ezedi on Thursday.
He is wanted on suspicion of attempted murder over the attack, which took place in Lesser Avenue at about 19:25.
The woman, who police revealed had been in a relationship with the suspect, remains sedated in hospital and there are concerns she may lose sight in one eye. Both children, aged eight and three, have been discharged.
Police said their thoughts remained with the mother, who was still “very poorly and unable to speak to police”.
The suspect, who is not the father of the children, suffered serious facial injuries in the incident which police had said could be fatal.
Ezedi is an Afghan refugee who came to the UK in a lorry in 2016.
He had his asylum claim rejected twice before he successfully appealed against the Home Office by claiming he had converted to Christianity.
Ezedi was also convicted of two sexual offences in 2018 but was allowed to stay because his crimes did not meet the threshold for deportation.