Ruling BJP MLA Rajkishore Keshri was on Tuesday stabbed to death allegedly by a woman visitor at his residence here on Tuesday.
Mr Keshri was meeting visitors at his residence when the woman identified as Rupam Pathak stabbed him, severely damaging his spleen which led to his death, director general of police Neelmani said.
Pathak was soon arrested, he said. deputy chief minister Sushil Kumar Modi strongly condemned the killing of his party MLA and said the matter was being probed thoroughly.
"All aspects involved in the incident will be looked into in course of inquiry," Modi said before leaving for Purnia.
Describing Keshari as "a popular leader", he said the incident should not be linked to "law and order" and "the probe will establish about the mental condition of the woman involved in the attack."
Meanwhile, state Congress leader Prem Chandra Mishra demanded a high-level probe into the incident.
RJD Secretary General Ramkripal Yadav also condemned the killing and said "in his (Keshari's) death, I have lost a close friend."