A woman who was prosecuted for trying to drown her baby son more than a decade ago has been accused of killing the now 12-year-old boy by drowning him in a canal.
Sheriffs deputies found the boy and his seven-year-old brother unresponsive in a full irrigation canal near a cornfield in California.
An autopsy showed Jackson Telnas died of drowning.
The younger boy is in hospital in a critical condition.
Sherri Renee Telnas, 45, was arrested in her rural home near Porterville, about 270 miles south of San Francisco.
An unnamed individual called 911 and told officials that Telnas was acting strangely and had taken the boys to a cornfield near their home, said Ashley Schwarm, a spokeswoman with the Tulare County Sheriffs Office in California.
Jackson had survived after Telnas first tried to kill him in a Montana river in 2008, authorities said.
She was soaking wet as she carried the boy, then 10 months, into a hospital and said she had tried to drown him because bad thoughts or voices told her to do it, Mineral County, Montana, Sheriff Mike Boone said in a statement.
She pleaded no contest to two counts of felony criminal endangerment and was sentenced in 2009 to the custody of Montana health officials for 10 years because of a history of mental illness, Boone said.
Jackson was living with his father at the time, the sheriff said.
She spent less than a year at the state psychiatric hospital, said Ellie Brown, who is married to the boys uncle.
Telnas got custody of Jackson in late 2010 as part of her divorce, court records showed.
The judge found that she was doing well in her treatment with her psychiatrist, was holding down a job and her relationship with her son appears to be very loving.
The psychiatrist had no concern about her ability to parent and testified that he sees no risk factors to indicate that she may de-compensate in her emotional wellness, District Judge Ed McLean wrote.