FORT WORTH, Texas -

(AP) - Criminal charges have been dropped against eight former North Texas police officers in an alleged overtime pay scam involving traffic tickets.

Tarrant County prosecutors on Friday announced the criminal counts against the ex-Fort Worth police officers were dismissed amid the unavailability of witnesses, lack of memory by some witnesses as time has passed and new evidence. Further details weren't immediately disclosed in the investigation since 2010.

The officers were indicted in 2011 on counts including tampering with a government record and theft by a public servant. The case involved when tickets were written, such as on regular duty, and whether the citations were altered to indicate overtime pay was deserved. The OT was available through a federal grant.

Fort Worth police Chief Jeff Halstead fired five officers. Three others resigned.