A man has been arrested in connection with the murder of a vulnerable man who was stabbed 102 times in Essex. James Attfield, 33, was found near Castle Park in Colchester on March 29.
Mr Attfield, who had a brain injury after being hit by a car four years ago, had been at the River Lodge pub in the hours before his death.
Essex Police said they had arrested and were questioning a 27-year-old man from Colchester. Officers have also raided two properties in the town as part of the investigation.
Detective Chief Inspector Simon Werrett said: "Two of the people featured in the CCTV images we have released have come forward and have been spoken to and eliminated from our inquiries.
"That still leaves 21 people who we need to speak with and who may hold important information in relation to our investigation."
A 27-year-old woman was arrested earlier this month and released on bail pending further inquiries.