A pensioner died 10 days after his dog was involved in a fight with another dog.
The 74-year-old is believed to have fallen and hit his head on a kerb during the incident in Turkey Road, Bexhill.
He did not report the incident to police or get medical help for any injury but was said to have been feeling unwell since it happened.
The man fell ill at his home in Jubilee Way last Wednesday and paramedics were called but were unable to revive him.
Detectives are trying to establish whether the incident, which happened between 10am and noon on Sunday, July 20, contributed to his death.
No description is available yet of the pensioner's pet, but it had been fighting with a Staffordshire bull terrier type of dog.
Detective Inspector Gavin Patch said: "We are trying to establish the circumstances of the victim's death and would like to hear anyone who may have seen two men with dogs in the Turkey Road area.”
Anyone with information should contact police on 101 or email email@example.com quoting Operation Cafe.