Beos, who gave three hours of testimony on Monday evening denying all charges against him, was detained in the early hours on Tuesday.
He was the third person to be detained following the owner of second-division club Ilioupoli, George Tsakogianni, and bookmaker Vassilis Karakoulia.
All three are accused of "directing a criminal organization, money laundering and criminal activity, repeated fraud over and above the amount of 15,000 euros."
In addition, charges of "extortion by threat of harm, repeated, bribery and corruption in altering the results of matches and participation in illegal betting" were also brought.
Doubts have now been cast over Olympiakos Volos' participation in the Europa League. The club is set to begin its campaign in the second qualifying round on July 14.
