Please help with this old horror movie!

i remember seeing a movie a while back, maybe about 15 years ago. all i remember from the movie is that there was a very creepy man, who would lure kids in to going with him. in one scene, he was at the park and had a tape recording of a dog. he approached a child and asked if the child would help him find the dog. in another (vague) scene, it shows him in a tunnel with a little girl’s dead body, and it flashes back to when he was killing her- he did so by smashing her head against the tunnel walls. these are literally the only scenes i remember and it has been killing me trying to describe it to people to figure out what the movie is called. please help!!

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