The case dropped on prescription after six years.
38 accused officers walked free following the recent ruling by Kırıkkale 2nd Court of First Instance.
Between 1998 and 1999, Ankara chief of police at the time Cevdet Saral and his deputies and 34 police officers have been accused of concocting an unknown, illegal surveillance room at the department's headquarters.
They followed numerous phone conversations without court orders.
Inspectors deepened the investigation and revealed that 963 people had been monitored illegally between May 1998 and May 1999.
Among them were high rank officials, workers' unions, the parliament, government officials as well as other political party administrators.
A case was filed by the public prosecutor's office following the investigation but only one deputy were condemned to a deferred six months imprisonment.
Others escaped penalties on allegations of misconduct. One of the eavesdropped, Evrensel daily journalist Sultan Özer filed a complaint against the Ministry of Interior and won. As she tried to recourse the decision to other suspects, the court dropped the file on prescription.(EÖ/EÜ)