PORTERVILLE, Calif. – A woman has been charged with murder after she allegedly killed her son over the weekend, a decade after she first attempted to kill the boy.

Sherri Telnas, 45, was arrested Saturday in Porterville (Calif.) after witnesses saw her acting "strangely" while walking her children to a field near her home.

When police arrived, they found Telnas' 12-year-old son dead and his 7-year-old brother injured. The surviving son was taken to the hospital where he is in critical condition.

Officials have not released how the boy was killed.

Telnas was convicted in 2009 of attempting to drown the same boy when she submerged herself and the then baby in a river. She admitted to authorties that she tried to drown the child.

After Telnas pleaded guilty to two counts of criminal endangerment, she was ordered to undergo mental health treatment, the New York Post reports.

The boy's father was given custody of his son a decade ago, but it's not know why he and his younger brother were with Telnas at the time of the incident.