The first took place near the Thames Path in Thamesmead, southeast London, in May 2020.
A second woman was attacked in June 2024 in a derelict area in Sewell Road, Abbey Wood, also in southeast London.
Investigators are now working through a list of men who share familial DNA with the suspect, compiled by the National Crime Agency.
The Metropolitan Police said they have been using that information to take voluntary samples from people across the country to rule out or highlight potential suspects.
CCTV of a man in a white vest, jeans and white trainers has also been reissued, while a £10,000 reward is on offer from Crimestoppers.
“This man has targeted two very vulnerable women, raping them in daylight hours in residential areas,” said Detective Chief Inspector Zoe Hendrick.
“Investigations of this nature are extremely rare, and our priority since the launch of the first investigation has been to support the victims and identify the man responsible.”
Read more from Sky News:
Teen left with potentially life-threatening gunshot wounds
Interns’ work ‘not properly checked’ at justice watchdog
Detectives followed up all information from a previous public appeal but were unable to identify the person in the CCTV.
“We’re back here again today, asking (for) further help from the public to come forward and give us any information,” said DCI Hendrick.
“People with circumstances (that) might have changed, or they might feel now that they can divulge information, or they might see this appeal for the first time.
“I’d just like to encourage anyone to come forward.”
Anyone who recognises the man, or has relevant information, can call police on 101. To stay anonymous, contact Crimestoppers on 0800 555 111 or online.
