Years after the verdict, a conviction for a 2003 murder appeared to be under threat.

An assistant district attorney, according to court filings, had discovered that trial prosecutors hid evidence undermining the credibility of testimony that Lavar Brown was an accomplice to the murder of North Philadelphia Rite Aid manager Michael Richardson. The lawyer learned that one of two witnesses who testified against Brown had falsely implicated a woman who was incarcerated at the time of the murder and the lie wasn’t disclosed.

Then, according to the filing, prosecutors decided to continue the cover-up.

Lawyers for the Philadelphia DA’s Conviction Integrity Unit (CIU) now say that a review of the case file revealed a “pattern of prosecutorial misconduct” and that Brown should get a new trial.

“Those documents not only paint a picture of an unfair trial, they also reveal the equally problematic actions of post-conviction prosecutors scrambling to maintain a conviction despite the clearly questionable conduct of the trial prosecutors,” the CIU lawyers wrote in a Nov. 1 filing in Philadelphia Common Pleas Court.

The filing included an internal DA’s Office email in which a supervisor described concealing prior witness statements as both routine and acceptable, and even proposing retaliation against a defense lawyer who provided information helpful to Brown.

The prosecutors who worked on the case insist they acted properly.