A Columbus man was sentenced to an indefinite prison term of between 12 and 13-and-a-half years in prison Monday in connection with a string of business robberies he committed last year.

David L. Au, 38, appeared before Delaware County Common Pleas Court Judge James P. Schuck Monday afternoon for a change of plea hearing and entered a guilty plea to four counts of robbery, second-degree felonies. According to the terms of the plea agreement, four charges of robbery, third-degree felonies, were dismissed.

The charges were in connection to a series of robberies that Au committed in February 2023. Prosecutors said he committed a robbery at a Lewis Center Turkey Hill location on Feb. 3 and Feb. 5; at the Donatos on Sandusky Street on Feb. 5; and at a Lewis Center Goodwill on Feb. 5. He was arrested by Delaware County and Franklin County law enforcement later that day and has been in the Delaware County Jail since.

At each location, Au either showed or brandished what appeared to be a firearm in order to get employees to give him money from the register or cigarettes. After his arrest, authorities learned the firearm was an airsoft gun loaded with fake ammunition to give it the outward appearance of a real revolver. No one was injured during the robberies, prosecutors reported Monday.

At the change of plea hearing, Au told Schuck that he was facing many stressors in his life at the time as well as mental health issues and said he feels remorse for “the victims and actions in my case.”

Au said he hopes to get his life back together while he is incarcerated.

Schuck sentenced Au to three years for each of the four charges as well as a term of one-and-a-half years to be served consecutively for a total prison term of between 12 to 13-and-a-half years.

He credited Au the 391 days he has spent in the Delaware County Jail and said upon his release, he will be subject to between 18 months and three years of post-release control. Schuck waived court costs in the case, and prosecutors said there was no restitution to be paid in the case.

Additionally, Au faces charges related to eight similar robbery incidents in Franklin County.

Au was in the Delaware County Jail Monday.

Additionally, Kaitlyn Penwell, of Logan, Ohio, was indicted on March 9, 2023, and charged with two counts of robbery along with Au for the Feb. 5 robbery at Turkey Hill. Her arraignment has not yet been set.

Glenn Battishill can be reached at 740-413-0903.