A fourth person has died after a serious collision involving a lorry, a minibus and a car on the M25 in Essex.
Three people died at the scene, between junctions 27 and 26 of the anti-clockwise carriageway, on August 23 and a fourth person later died of her injuries, Essex Police said.
The four dead were all passengers on the minibus.
Two men, the drivers of the minibus and the lorry, were arrested on the day of the collision.
Essex Police said the minibus driver was “de-arrested following new information”.
The lorry driver, a 64-year-old man from Ipswich, was arrested on suspicion of causing death by dangerous driving, causing serious injury by dangerous driving, and driving while unfit through drink or drugs.
He has been released under investigation.
The force has provisionally released names of the four dead, awaiting formal confirmation from the coroner.
Abigaile Muamba, 31, from Edmonton Green, north London, Dexter Augustus, 60, from Waltham Forest, north-east London and 59-year-old Jennifer Smith from Stratford, east London, were all pronounced dead at the scene.
Lisa Gardiner, 44, from Walthamstow, north-east London, later died of her injuries.
Inspector Mark Fraser, who leads the force’s serious collision investigation unit, said: “Our thoughts are with the families and loved ones of those who lost their lives in this awful incident.
“My officers are working tirelessly to try and piece up what led to the collision.
“If you saw the three vehicles prior to the collision, a Mondeo, a minibus and a lorry, or have any dash cam of their movements, please contact us.
“We need to get to the bottom of what happened.”
The collision happened just after 6.15pm.
Police are urging witnesses with dashcam footage to submit a report at https://www.essex.police.uk, or call 101 citing incident 972 of Monday August 23.
Information can also be given to Crimestoppers anonymously on 0800 555 111 or https://crimestoppers-uk.org