Joel Eldridge, 29, from Bexhill, was living in Macieira, near Serta in Portugal, when his family last heard from him in mid-July last year.
Sussex Police said officers were informed of his disappearance in late August 2018, with a public and media appeal launched for information.
The force said on Tuesday that Portuguese officers had discovered a body near the town of Picha.
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Mr Eldridge travelled to Portugal in January last year, saying he was going to work on a house near Coimbra, police said.
He also contacted a UK-based firm about potential work back in the UK on July 26 2018.
Detectives from Surrey and Sussex Major Crime Team and officers from the National Crime Agency have been working on the case alongside counterparts in Portugal.
Detective Chief Inspector Chris Friday, of Surrey and Sussex Major Crime Team, said: ‘Our inquiries, supporting those of the Portuguese investigators, gave us cause to believe that Joel had come to harm at the hands of others while in Portugal.
‘We understand that further tests are needed to confirm that the body is that of Joel, but we suspect this to be the case and we have updated his family about this development.
‘Our thoughts are with them at this sad time.’
Mr Friday said the Portuguese Judicial Police continued to lead a murder investigation and appealed for anyone in the UK who heard from Mr Eldridge or has information about him to contact Sussex Police through the force website, or to call 101 quoting Operation Lyra, or contact Crimestoppers anonymously on 0800 555111.