ABILENE, Texas -

The investigation into synthetic drugs in Abilene has progressed to the federal level.

Since 2012, KTXS News has reported on the rise of synthetic drug overdoses and the city's efforts to stop the problem.

In undercover operations, federal agents say they purchased – on several occasions – illegal formulas of synthetic drugs at Mr. Nice Guy's two Abilene locations, 1601 Butternut and 2641 S. 14th Street.

During the investigation, federal agents seized money and property worth more than $700,000. A filing Friday in federal court in Dallas started the formal forfeiture of those assets.

"This investigation actually began several years ago,” Abilene Police Chief Stan Standridge said. “It culminated with some significant seizures at Mr. Nice Guy's. They actually had two locations.

“We worked collaboratively with the Drug Enforcement Administration and those efforts were recently filed in federal court in the Dallas office."

According to the Complaint for Forfeiture filed in federal court, the owner of Mr. Nice Guy's – Ricardo Cervantes Estrada – is serving both federal and state prison sentences for an unrelated conviction of engaging in organized criminal activity.

The filed documents state Estrada has continued to manage and operate the businesses from jail, communicating with employees over the phone and through mail.

Since the Abilene Police Department’s crackdown began, Standridge said the number of synthetic drug overdoses has dramatically decreased.