OMAHA, Neb. (AP) — The second of two former Black Panthers who always maintained their innocence in the 1970 bombing death of a white Omaha police officer has died in prison.

A spokesman for the Nebraska Department of Correctional Services said Friday that Ed Poindexter had died a day earlier at the age of 79. David Rice, the other man convicted in the death of Omaha Police Officer Larry Minard, died in prison in 2016.

The pair argued that they were targeted because of their membership in the Black Panthers by an FBI program that undermined radical political groups, and they questioned the legitimacy of crucial testimony that helped convict them.

Poindexter and Rice both doubted the key witness in the case who implicated them in the bombing plot, but they were unsuccessful in numerous appeals. A recording of the phone call that lured Minard to a vacant house before a homemade explosive detonated appeared to have been made by an adult man even though a teen testified he made the call.

And a voice expert who analyzed it years later as part of one of Poindexter’s appeals said it was “highly probable” that the recording didn’t match the voice of the witness, who was granted immunity in exchange for his testimony. That teen testified that Poindexter and Rice directed him to plant the suitcase loaded with dynamite.

The recording of that police call was never played at trial, and in one of his appeals Poindexter said his lawyers at the time never even requested a copy of it.

But various judges decided the doubts about the recording raised later weren’t enough to warrant a new trial, and Poindexter and Rice’s life sentences were upheld. The Nebraska Pardons Board also refused to commute their sentences despite pleas from advocates.

Poindexter’s death will be investigated by a grand jury, as required by state law, though officials said he was being treated for an unnamed medical condition before he died. In an appeal to Nebraska’s newly elected governor a year ago, Poindexter’s advocates said he had advanced kidney disease and had been diagnosed with Parkinson’s disease.