The Clapham chemical attack suspect is most likely dead, police say, as they plan to search the River Thames for his body.
Abdul Ezedi, who went on the run more than a week ago, was believed to have "gone in the water" a few hours after the violent incident in south London on Wednesday 31 January.
He was seen leaning over the railings of Chelsea Bridge in west London that night - but the Metropolitan Police admits his body may never be found because of the speed of the current.
The suspect is accused of pouring a strong alkali on his ex-partner, and also injuring her two daughters, aged three and eight, in the attack at 7.25pm that left a total of 12 people wounded.
The last sighting of 35-year-old Ezedi was on Chelsea Bridge just before 11.30pm.
He crossed over the bridge and entered Battersea Park, then crossed back over the same bridge minutes later.
The force said he "walked with purpose" before the bridge and then "his behaviour visibly" changed.
"He walks up and down and can be seen leaning over the railings," said a Met spokesman.
No CCTV of the suspect was seen after this point, the force confirmed.
Commander Jon Savell said Ezedi's body may never be found due to the river's strong current.
He said: "At this time of year, the Thames is very fast flowing, very wide and full of lots of snags.
"It is quite likely that if he has gone in the water, he won't appear for maybe up to a month and it's not beyond possibility that he may never actually surface."
Detective Superintendent Rick Sewart said the Met had tracked Ezedi's movements from the Tower Hill area, where he has walked more than four miles "with purpose" to Chelsea Bridge.
Asked whether police were willing to say that Ezedi was dead, Mr Sewart said: "I'm prepared to say that he's gone into the water and if he's gone into the water then that's the most probable outcome."
Had Ezedi not gone into the water, officers would have had a high degree of confidence in finding him, Mr Savell added.
A behavioural psychologist commissioned by the police viewed the footage and believes it was possible he could have taken his own life.
The Clapham attack involved a corrosive alkaline substance and Ezedi's ex-partner's injuries are thought to be "life-changing".
She may lose the sight in her right eye and remains sedated in hospital, still too ill to speak to police.
The Met has said the breakdown of the relationship could have been a motive for the assault.
After the attack, the Met launched a manhunt for Ezedi, with assistance from the British Transport Police and officers with Northumbria Police in Newcastle, where he lived.
Police had warned the public that Ezedi was "dangerous" and should not be approached while it was thought he was on the loose.
The attack on Lessar Avenue, near Clapham Common, was captured on CCTV.
Ezedi arrived in the UK via a lorry in 2016 and claimed his life would be in danger if he returned to his native Afghanistan.
He was convicted of two sexual offences in 2018 but was allowed to stay in the UK because his crimes were not serious enough to meet the threshold for deportation.
The investigation continues with a "significant number of people" dedicated to finding out what happened.
A Marine Policing Unit will be carrying out boat searches at low tide in the area over the coming days, police said.