(KAIR) -- Around 18 months after an Atchison grain elevator explosion killed six people; federal prosecutors now are considering criminal charges against the owners.

According to the Kansas City Star, OSHA has referred the case for criminal prosecution against Bartlett Grain and/or its top officials.

The criminal investigation began about three months ago.

Bartlett responded to the Star about the criminal investigation, citing that they have “…met with the U.S. Attorney’s Office since that referral, as is standard practice, and has pledged its complete cooperation. Bartlett Grain respects the confidential nature of the inquiry and, thus, cannot publicly discuss this matter further until the U.S. Attorney’s Office has completed their review.”

On April 12, 2012, OSHA issued multiple citations to Bartlett, totaling 406 thousand dollars.

Bartlett has stated that they are fighting the fines, claiming the citations are “flawed.”

In the response to the Star, Bartlett states “…In the year following the accident, Bartlett Grain brought in a team of the country’s most knowledgeable engineers and explosion experts, and their extensive investigations concluded that OSHA’s citations were not only mistaken but, in fact, those findings could not have contributed to the accident. Bartlett Grain anticipated and understood we would have an opportunity to prove all of this to OSHA. At every stage, however, OSHA declined to discuss their allegations with Bartlett Grain. Ultimately, on the eve of a mandatory mediation at which Bartlett Grain finally would have had a chance to discuss the merits of OSHA’s allegations, OSHA put the matter on hold and made its referral to the U.S. Attorney’s Office based on ‘standard policy.”

The fines have been put on hold pending the criminal investigation.

Also currently in limbo is a civil suit in Jackson County Circuit Court filed by four of the six families of the victims against Bartlett and their President, Bob Knief.

This isn’t the first time OSHA has pursued federal charges against a Kansas grain elevator.

A 1998 blast at a Wichita elevator owned by North Kansas City-based DeBruce Grain killed seven workers.

OSHA asked for criminal charges, alleging DeBruce knowingly and “willfully” disregarded workplace safety rules that could have prevented the deaths.

However, federal prosecutors in that case declined, and OSHA then negotiated a settlement, drastically dropping its civil fines against DeBruce.