Everything I can remember:
The kidnapper is a Male
It’s mostly from cops/fbi/detective point of view with snippets to the kidnappers actions, theyre trying to find and catch him.
It never shows him with the victims aside from the kidnapping parts.
I believe all of the victims are children and I think they are all girls.
He lures one of his victims with a recording of a dog barking and asks her to help him find it, i believe in a park near woods. The “dogs” name was something like snuffles, or another commonly used name but at some point it does show you the recorder so you know it’s fake.
Another child he gets at a petting zoo or very similar crowded place and they catch it on video he gets her right under the parents noses.

Things I can’t remember for sure but I am thinking they are a part of this movie but could possibly be mixed with another:
When they finally catch him it is in a big storm drain or in a sewer and theyre splashing in the water (ankle deep)
They also might find some of the bodies in the water
I think at one point they show inside his house and he has a goldfish
I’m not sure if it ever really shows his face well, maybe at the end in the big showdown.

I would put this to be mid 90s but definitely not before 1980 and not after 1999. I *think* there is one main cop or detective on the case and he is also male but I’m just having a hard time remembering much besides the way he kidnapped the children.