The owner of a Georgia peanut processing plant knew he was shipping salmonella-tainted products, according to evidence presented at a congressional hearing this week.

Stewart Parnell, owner of Peanut Corp. of America, instructed employees to ship peanut products he knew to contain deadly salmonella because he was concerned about lost sales, e-mails revealed at a congressional investigative panel Wednesday. The peanut products in question were used primarily in institutional settings, such as nursing homes and hospitals, and have lead to more than 600 illnesses and contributed to at least eight deaths. One victim, a 72-year old nursing home resident in Minnesota, survived cancer only to succumb to salmonella poisoning four days before Christmas.

During questioning, Parnell invoked his Fifth Amendment rights, which allow him to refrain from delivering self-incriminating evidence, according to news reports from the hearing. Peanut Corp. Of America is facing numerous lawsuits in connection with the outbreak, and investigations continue on state and federal levels.