SANTA CLARA COUNTY (KRON) — The defense of Sierra LaMar’s convicted killer, Antolin Garcia-Torres, is arguing that he may have been exposed to harmful pesticides, like perchlorates and “possibly” mercury.

The penalty phase of the murder trial continued Monday. The jury will have to decide whether Garcia-Torres will get the death penalty or life in prison.

Garcia-Torres, 26, was convicted May 9 of the 2012 murder of 15-year-old Sierra LaMar as well as the attempted kidnappings of three women in 2009.

The convicted killer grew up in a shack in the middle of the San Martin strawberry fields where his Mexican-born parents picked fruit.

On Monday, his mother, Laura Torres, testified through tears Monday morning, describing through two Spanish-English interpreters the horrors of poverty, abuse, and loss that have ravaged her family for decades.

She also testified about her exposure to pesticides when she worked in fields while she was pregnant with Antolin.

Garcia-Torres’ cousin, Armando Garcia, also took the stand on Monday. He said he also worked in the field with Torres where pesticides were used.

The defense is expected to call on a toxicologist to testify on Garcia-Torres’ pesticide exposure.