I need the communities help dealing with an aggressive PokemonGo Player

I recently moved my family into a new apartment that is next door to a municipal park (10min walk - 2min drive away). Over the past year we have gone to this park almost daily to get the kids outside and moving. We are the only regulars at this park and in that time our children have become obsessed with Pokémon and PokemonGo. Best of all they were willing going outside in their free time and are having fun playing with the other kids in the park!

These last 6 months we have been dealing with an adult that has become increasingly more aggressive towards my family, our kids, and their friends that are playing this PokemonGo game. It has escalated to the point that this man has made threats of harming my family, taken photos of our cars/license plates, following us back to our building from the park and even followed us to a neighboring townships park 20min away when we took the police's advice to "go somewhere else for a while". Driving around the neighboring town we noticed that this guy is in almost every Pokémon gym in the area.

Two months ago my son had to call the police to the park when this guy drove his car into the fence around the playground from pulling into the park too fast and not being able to stop. My children were the only ones in the park at the time and battled one of the 3 gyms that this guy was holding for over 16hours, he arrived at the park in under 2min. When the police arrived they got this man to leave but our children were/are still shaken from the encounter. They each have mace in their bags now and are not allowed at the park alone anymore.

Over the last months we have been talking to the state police and a lawyer about pressing stalking or harassment charges but they discouraged it saying that we don't have proof of the threats and that the videos are not enough because its a public park. The police insisted that this guy was just here to play Pokémon and they would just talk to this guy and tell him to stop harassing people. This has worked to an extent, he no longer sits in his car the whole time we are at the park and is no longer waiting nearby for when we typically get there after school. But now has begun "GPS Spoofing" his player into the park and taking the gyms back as soon as he gets beaten.

Despite multiple in-game reports and police intervention, this man is unrelenting and is dead set on controlling PokemonGO in the area. The kids are much less enthusiastic about going outside to the park and Pokemon in general.

Any advice on how to handle this person/situation is appreciated