The Argentine lost his life along with pilot David Ibbotson on 21 January after the aircraft taking the pair from from Nantes to Cardiff disappeared off Alderney.
As reported by the BBC, a spokesperson for Dorset Police has stated a 64-year-old man from North Yorkshire had been arrested and released while investigations continue. Tthe families of the two men who died have been informed of the arrest.
Det Insp Simon Huxter, of the forces Major Crime Investigation Team, said: "As part of this investigation we have to consider whether there is any evidence of any suspected criminality and as a result of our inquiries we have today, Wednesday 19 June 2019, arrested a 64-year-old man from the North Yorkshire area on suspicion of manslaughter by an unlawful act.
"He is assisting with our inquiries and has been released from custody under investigation."
Sala had joined Premier League side Cardiff on a three and a half year deal for a club record transfer fee in the region of £15m on 19 January. With the move agreed, despite a late bid from a club in the Chinese Super League, Sala was set to fly to Cardiff to join up with his new teammates.
Upon the disappearance of the aircraft carrying Sala and Ibbotson, a search was conducted to find the plane. After three days of unsuccessful searching, the search was called off.
Worldwide calls were made to continue the search, with footballers and members of the public donating to allow the search to continue. On 9 February a body was discovered that was confirmed to have been Salas, with his former club Nantes subsequently retiring his former number nine jersey.