After the stabbing, neighbors told the police they saw a man wearing a bandanna watching Ishii's home from around 8:50 a.m.
Neighbors said they heard Ishii shouting at someone, then heard him screaming. His Russian-born wife Natalia was at home at the time of the attack, but was unhurt, the police said.
Ishii was active in exposing various money scandals including those involving Muneo Suzuki, a lawmaker who was all but ousted from Prime Minister Junichiro Koizumi's ruling Liberal Democratic Party in March.
Ishii also played an active part in exposing the activities of the Aum Shinrikyo cult in Russia. Prior to becoming a politician, he studied law and philosophy at the postgraduate school of Moscow University.
Commenting on the murder, Koizumi told reporters at his office, "Hindering political activities by violence or assassination is intolerable under any circumstances. I feel strong resentment."
DPJ President Yukio Hatoyama told reporters in Nagaoka, Niigata Prefecture, "I was shocked. He was a man with sense of justice and continued to fight against evil."
Neighbors said they heard Ishii shouting at someone, then heard him screaming. His Russian-born wife Natalia was at home at the time of the attack, but was unhurt, the police said.
Ishii was active in exposing various money scandals including those involving Muneo Suzuki, a lawmaker who was all but ousted from Prime Minister Junichiro Koizumi's ruling Liberal Democratic Party in March.
Ishii also played an active part in exposing the activities of the Aum Shinrikyo cult in Russia. Prior to becoming a politician, he studied law and philosophy at the postgraduate school of Moscow University.
Commenting on the murder, Koizumi told reporters at his office, "Hindering political activities by violence or assassination is intolerable under any circumstances. I feel strong resentment."
DPJ President Yukio Hatoyama told reporters in Nagaoka, Niigata Prefecture, "I was shocked. He was a man with sense of justice and continued to fight against evil."