The school principal of the Indian school who served free lunch to its students, yet some unfortunately died due to pesticide poisoning, has been arrested on Wednesday.

And if found negligent and convicted of the untimely deaths of 23 children, Meena Devi, headmistress of the Dharmasati Gandaman Primary School in the village of Marakh in Saran district in the eastern state of Bihar, will face the "full force of the law," Nitish Kumar, chief minister of Bihar state, said.

"This is not a simple case of accidental poisoning," Mr Kumar said in a news conference. "The police are investigating the case. They have arrested the key accused. It is a matter of further investigation."

Dharmasati Gandaman Primary School students were treated to a free lunch meal on July 16, a known strategy meant to entice the students and their families to attend school. But the apparent good deed turned sour when a total of 23 children died from food poisoning due to the rationed food which was found laced with pesticide.

Read: Free School Lunch Kills 20 Children in India

In hiding for nine days, Ms Devi was finally arrested Wednesday morning after police received a tip of her whereabouts.

"She is now being interrogated in the Chhapra police station and will appear before a magistrate tomorrow," the LA Times quoted Abhijit Sinha, the district magistrate in Chhapra, as saying. "Medical teams have been dispatched to help the grieving parents."

Tests conducted by forensic authorities discovered high levels of monocrotophos, a highly toxic organophosphate insecticide, in the free lunch meal consisting of rice, beans, potato curry and soy balls. It was reported that it was Ms Devi herself who bought the cooking oil from a store owned by her husband.

Police theorised that her husband might have stored the cooking oil in a container once filled for pesticide purposes.

Ms Devi could have probably earned sympathy from the parents of the dead children and from the whole of India had she immediately attended to the sick poisoned students of her school.

Instead, according to villagers and state officials, she left, leaving the ill children to fend for themselves. Some of the children who managed to stagger home died in the arms of their parents.

In the same news conference, Mr Kumar vowed to help those who are affected.

"We can't bring back the dead children," he said, "but we will do whatever we can for the development of the village and to help the families."