Attorneys for a couple who claim Monsanto’s Roundup weed killer gave them both cancer tried to convince a California jury Thursday that the agrochemical company engaged in decades of fraud to hide the fact that the herbicide is carcinogenic.

Plaintiffs’ attorney Brent Wisner made explosive new allegations about the Bayer AG unit during opening statements in the joint trial of Alva Pilliod, 76, and Alberta Pilliod, 74, a married couple from Livermore, California, diagnosed with non-Hodgkin lymphoma four years apart who claim that their 35 years spraying Roundup on their residential properties gave them the disease.

“The product started in fraud and the evidence will show it is still going on today,” said Wisner, of Baum Hedlund Aristei Goldman in Los Angeles.

Alva was diagnosed with systemic non-Hodgkin lymphoma in 2011 and has been in remission since, after undergoing aggressive chemotherapy treatment that degraded his cognitive function, said Wisner.