An Oklahoma man who tried to blow up a bank has been sentenced to 25 years in federal prison.

Jerry Varnell was accused of attempting to copy the Oklahoma City bombing in 1995, one of the deadliest attacks in modern US history, according to CBS News.

Federal prosecutors said Varnell wanted to use an explosive device similar to the one that was detonated outside a federal building in Oklahoma City, killing 168 people, Reuters reported.

They accused Varnell of trying to detonate what he thought was a 1,000-pound ammonium nitrate bomb in an alley beside BancFirst in downtown Oklahoma City in 2017.

He was convicted in February 2019 of trying to use a weapon of mass destruction and other crimes and on Monday was sentenced.

Varnell’s arrest took place after an eight months long domestic terrorism investigation led by the FBI, Reuters said.

In the investigation, an undercover agent was said to have posed as a co-conspirator and agreed to help Varnell build what he believed was a 1,000-pound (454 kg) explosive.