Afrobeats artist Castro, whose real name is Theophilus Tagoe, went missing, along with friend Janet Bandu, in July.
They disappeared while using jet skis on holiday with former Sunderland striker Gyan’s family in the Ghanaian coastal town of Ada.
Allegations in Ghana’s media suggested the disappearance was suspicious.
Castro and Bandu were last seen heading towards the ocean on a jet ski and were presumed drowned.
No bodies were recovered and rumours continued to circulate this month when Gyan’s brother, Baffour Gyan, was alleged to have been part of a gang which attacked a journalist who had asked the player about the rumours. The assault charges on Baffour Gyan have now been dropped.
The speculation prompted 28-year-old Gyan, who joined United Arab Emirates side Al-Ain in 2011, to hold a press conference.
His lawyer Kissi Agyabeng said the family had been “dismayed” and had remained silent until now as they did not want to interfere with police investigations.
The statement read: “What sells in the media, and what indeed sold and is still selling in the media in Ghana are wild allegations and rumours directed especially at Asamoah Gyan – ranging from the absurd – of the imputation of criminality to him in the sense that he either murdered Castro or had him kidnapped – and ending with the ludicrous – that he sacrificed him spiritually to enhance his career.”