Police divers have been deployed as part of the investigation into the disappearance of 19-year-old student Richard Okorogheye.
Mr Okorogheye, who has sickle cell disease, left his family home in the Ladbroke Grove area of west London on the evening of Monday March 22, and was reported missing two days later.
He was last seen on CCTV in Loughton, Essex, in the early hours of Tuesday March 23, walking towards Epping Forest.
The Metropolitan Police said the search of the woodland continued for a fourth day on Sunday but nothing of relevance to the investigation has been found.
Police divers have been deployed and were seen in one of the bodies of water in the woodland in north-east London.
Scotland Yard previously said that detectives continue to keep an open mind about the Oxford Brookes University student’s whereabouts.
Initial police inquiries identified Mr Okorogheye leaving his home address and heading in the direction of Ladbroke Grove at around 8.30pm.
In a previously confirmed sighting on Monday March 22, Mr Okorogheye was seen boarding the number 23 bus southbound in Ladbroke Grove at 8.44pm.
CCTV footage shows he was wearing all black and had a black satchel bag with a white Adidas logo, worn across his lower back.
Police said further inquiries have established that he then took a taxi journey from the W2 area of London to a residential street in Loughton.
He was captured on CCTV walking alone on Smarts Lane, Loughton, towards Epping Forest at 12.39am on Tuesday March 23.
On Thursday, the force said Mr Okorogheye’s phone has not been in use since his disappearance.
Anyone with information is asked to call police on 101 quoting 21MIS008134.
Mr Okorogheye’s mother Evidence Joel previously said that her son had spoken of “struggling to cope” with university pressures and had been shielding during the Covid-19 lockdown.
As someone with sickle cell disease, Mr Okorogheye would only leave the house to go to hospital for regular blood transfusions for his condition.