Middlesbrough have signed Abel Xavier until the end of the season after he served a 12-month drugs ban.
Xavier has impressed on his return to Middlesbrough
He was suspended after testing positive for a performance-enhancing steroid dianabol after Boro's Uefa Cup trip to Xanthi in September 2005.
But the 33-year-old Portugal defender has played two reserve games and has now agreed a permanent contract.
Boro manager Gareth Southgate said: "He's served his ban and wants to force his way back into the side."
Southgate added: "In no way do we condone the taking of drugs, but the ban was reduced by the game's governing bodies, which suggests there was a significant reason for that.
"I'm a believer that people in life who serve a sentence should get the opportunity to rebuild their life or career afterwards.
"Andrew Davies has been playing particularly well, so for the moment he will have to be patient."
Xavier, who joined Middlesbrough from AS Roma in August last year, became the first Premier League player to be banned for doping when he failed a drugs test.
Originally banned for 18 months, his suspension was cut to 12 months by the Court of Arbitration for Sport in July.
Born in Mozambique, Xavier has played 20 times for Portugal and had spells with Benfica, Bari, PSV Eindhoven, Everton and Liverpool.