Wednesday marked Samuel Lightsey’s fourth day of testimony in the trial of his former boss at Peanut Corporation of America, Stewart Parnell, and two others. Peanut Corporation is blamed for a deadly 2008-09 salmonella outbreak that caused one of the largest food recalls in U.S. history.

Lightsey testified about documents that showed positive tests for Salmonella; emails sent by company employees to customers telling them to hold the product because of “inconclusive” tests, which Lightsey said were actually positive; and documents that showed water sometimes got into the company’s product, which he said can lead to contamination.

Defense attorneys have not yet started questioning Lightsey, who managed the plant from July 2008 until the company went bankrupt in 2009 following the outbreak. He pleaded guilty to seven criminal counts in May after reaching a deal with prosecutors.