A Cleveland Police spokeswoman said the 22-year-old man arrested in connection with the incident has been released on bail.
The injured man remains in an induced coma in hospital, police confirmed.
Officers say they have been searching for all evidence from the scene. It is unclear whether they have found the missing penis.
More top news
Police have seized 539 units of alcohol from drinkers as young as 15 in a bid to crack down on underage bingeing.
"Big Sam" was spotted letting his hair down in the seaside resort weeks after securing Premier League survival for Sunderland.
A look ahead at the Bank Holiday forecast for the Tyne Tees region.