The irrigation ditch near a cornfield where the children were found unresponsive. KFSN

Sherri Telnas, 45, faces murder charges for killing one of her 12-year-old son and seriously injuring her seven-year-old son. Tulare County Sheriff's Office

FRESNO, Calif. (KFSN) -- A mother faces murder charges for killing one of her children and critically injuring a second.The Tulare County Sheriff's Office says they were called to a home on Avenue 184 near Road 208 near Porterville between 4:30 am and 5:30 am Saturday.The caller said that a woman, 45-year-old Sherri Telnas was acting strangely and had taken her two young boys, ages 7 and 12 to a field across the street from their home.The caller felt something was wrong, so they went looking for Telnas and discovered the two boys in a full irrigation ditch near a cornfield and were not responsive.A neighbor and the boy's grandmother did CPR until deputies arrived moments later. The deputies provided medical aid to the boys until they could be rushed to a hospital.The 12-year-old boy died from his injuries.The seven-year-old boy is listed in critical condition and is being treated at Valley Children's Hospital.Sherri Telnas was taken into custody at the scene without incident and now faces murder charges.Family members that Action News spoke to said that Sherri has a history of mental health problems.She was previously incarcerated in Mineral County, Montana for criminal endangerment after attempting to drown her 10-month-old baby.That child, now 12, is the little boy who died Saturday. The family added the incident stemmed from mental illness."She is a criminal, but she does have underlying mental health disease, and she needs help," said psychiatric nurse practitioner Deborah Moore. Statistics estimate close to 25 percent of the U.S. population suffers from some mental illness, but those are only the reported cases."Look for signs of depression look for isolation, withdrawal, poor hygiene not taking care of themselves and their kid's neglect," Moore said.The child's cause of death has not yet been released as an autopsy is performed.This case is currently under investigation by the Tulare County Violent Crimes Investigation Unit, anyone with information is encouraged to contact Detective Miguel Franco or Sgt. Gary Marks at 559-802-9563 or 800-808-0488.