A suspicious man in black clothes was repeatedly seen near the site where a 7-year-old girl was found dead Monday in Niigata, local officials said Saturday.
Tamaki Omomo is believed to have been murdered on the same day her body was found on the train tracks.
She told a friend earlier in the day that she had been approached by a man in black clothes and sunglasses while on her way to school.
The police have been investigating that lead.
According to an education board official, a man wearing black clothes and a black mask was seen on a street talking to himself near her school on Tuesday afternoon.
On Wednesday evening, a junior high school girl was chased by a man whom she described as in his 50s, on a street about 2 km from Omomo's school.
She also described the man as wearing black clothes, the official said.
According to a police autopsy, Omomo was strangled. Her body was found by the railroad tracks after being struck by a train on Monday night.
Omomo left her elementary school with a friend at about 3 p.m. Monday. When she failed to return home by the evening, her mother contacted the police.
Bruises on Omomo's face suggest that she was strangled some time before she was struck by the train at about 10:30 p.m.
As another train had passed along the tracks about 10 minutes earlier without incident, the police believe the girl's body was placed on the tracks during that time frame.