Serial killer Stephen Port has lodged an appeal against his murder convictions.
Port, now 43, was sentenced to a full life jail term in 2016 after being found guilty of four murders and a string of sexual offences against seven living victims.
The Court of Appeal confirmed that Port had made an appeal and said it was in the early stages.
The families of Port's victims said the appeal "changes nothing".
The BBC understands that Port, who is originally from Barking in east London, is not currently legally represented.
Appeals against criminal convictions are supposed to be made within 28 days of conviction.
After lodging an appeal - by submitting the relevant papers - a judge must review the documentation before deciding whether to give the applicant permission to proceed.
Port's appeal is at this initial stage and has not yet been reviewed by a judge.
It is understood that Port is appealing against his murder convictions, but not against those for his sexual offences.
Image copyright MET POLICE Image caption Anthony Walgate (L) and Gabriel Kovari (R) were Port's first victims
A spokeswoman for the families of Port's victims said they "remain assured of the safety of Port's conviction. This changes nothing."
Between June 2014 and September 2015, Port murdered Anthony Walgate, 23, originally from Hull, Gabriel Kovari, 22, from Lewisham, Daniel Whitworth, 21, from Gravesend, Kent, and Jack Taylor, 25, from Dagenham, east London.
He was convicted by an Old Bailey jury after a seven-week trial.
Image copyright MET POLICE Image caption Daniel Whitworth (L) and Jack Taylor (R) were also killed by Port
Police ignored a series of chances to catch him sooner.
The Independent Office of Police Conduct (IOPC) recently concluded an investigation into potential misconduct by 17 Met Police officers who worked on the initial inquiries into the Port murders.
The IOPC report has been passed to the Met Police, which must decide how to respond to the watchdog's recommendations.