Police have formally identified a headless torso found in Regent's Canal near Hackney's Broadway Market as Gemma McCluskie, the missing former EastEnders actress.
A 35-year-old man is being held over her disappearance.
The latest development came days after police searching for the actress concluded DNA tests the torso found in the London canal on Tuesday.
There are reports that McCluskie's ill mother, who she cared for, is unaware of her death.
She played Kerry Skinner in 30 episodes of EastEnders in 2001 and also appeared in children's TV programme North and South.
Actors and Actresses that worked alongside McCluskie in EastEnders have been paying tribute to the 29-year-old on Twitter.
Brooke Kinsella, who has led a high profile campaign against knife crime after her brother Ben was murdered, tweeted:
Joe Swash, who played Mickey Miller in the soap, and was crowned King Of The Jungle on ITV's I'm a Celebrity Get Me Out Of Here wrote:
Detective Superintendent Fiona Mallon, who is leading the Scotland Yard investigation, said: "It is important that we piece together Gemma's movements from Wednesday February 29 until the discovery in Regent's Canal in Hackney on Tuesday.
"We also urge anyone with any significant information about this case to contact us as soon as possible. In particular we would like to hear from anyone who may have seen any suspicious activity around her home address in Pelter Street in Bethnal Green."
According to police she was killed after attending the opening of the new £650m Royal London Hospital, in Whitechapel, east London.
In a statement the force said: "She was pictured at the event wearing a yellow long-sleeved top with a round neck and navy-blue leggings. She was also carrying a Louis Vuitton bag with beige handles and brown-coloured end panels. She was also thought to be carrying her blackberry mobile phone which had a white phone case. These items have not been recovered."
Anyone who may have seen anything suspicious around the Regent's Canal area in Hackney, or who has any information, should call the Incident Room on 020 8345 3985; if you wish to remain anonymous, contact Crimestoppers on 0800 555 111.
See CCTV images of the actress below: