The 28-year-old striker, who had signed to Cardiff City, died in a plane crash in January along with pilot David Ibbotson.
-> Tories accused of "wrecking" motion to declare a climate emergencyDorset Police said a man aged 64 had been arrested from the North Yorkshire area.
Detective Inspector Simon Huxter, of Dorset Police's Major Crime Investigation Team (MCIT), said: "We have carried out a wide-ranging investigation into the circumstances of the death of Mr Sala and continue to work with partner agencies including the Civil Aviation Authority.
"As part of this investigation we have to consider whether there is any evidence of any suspected criminality and as a result of our enquiries 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 enquiries and has been released from custody under investigation.
"This matter therefore is still subject to a live investigation and I would ask the media and members of the public to refrain from speculation, as this could cause additional distress to the families involved as well as potentially hinder the investigation.
-> Yorkshire climber fell 1,300ft in mini avalanche on Ben Nevis as friend died in the tragedy"As is standard practice, we will not be releasing any further information as to the identity of the individual who has been arrested unless that person is charged to appear in court and again would discourage any speculation in relation to this."