As far as the dutch news reports, one of the three arrested was released because he was not in any way connected to the two others or the supposed hijacking. The two others are still detained, their houses searched, computers confiscated. They planned a 22 day vacation, but missed their flight from Amsterdam to Bodrum. They were able to book another flight from Rotterdam (the one they were on). A call was made the 112, the alarm number, that the two were planning a hijack. This forced the authorities to halt the plane, but apperently the crew or the airline were not told the specifics, only that a call was made. They tried to explain it to the passengers as a technical fault (for 5 hours).
Latest news is that a (other) third person, an (ex) friend of the two arrested, made the phone call, out of revenge because he was not allowed to visit the two anymore. He seems to be a drugaddict, used to be on friendly terms with the couple, but recently had a fight of some sorts...