A Kentucky trucker sentenced to more than five decades in prison for a crash that killed six is seeking a new trial, with defense attorneys arguing the state of Tennessee concealed crucial evidence.

Benjamin Brewer, age 42, was found guilty of six counts of vehicular homicide, four counts of reckless aggravated assault and individual counts of speeding and driving under the influence in the crash on I-75 near Ooltewah in 2015.

Brewer’s attorneys now want information on a chemical the Tennessee Bureau of Investigation added to his blood sample, asserting they’d never heard of the “contamination” until witness testimony.

Citing that and a second test showing lower levels of illegal drugs in Brewer’s system, his attorneys say he should be acquitted or given a new trial. They’ve subpoenaed prosecutors for communications with the TBI about the substance.

Prosecutor Neal Pinkston says the defense hasn’t proven the materials sought are relevant.