Abusive Ex Is Ramping Up Stalking And The Whole House Fears For Their Life - What Can We Do?

Hello! Im completely new to reddit so sorry if this post is weird but I’m in a bit of a situation and could use some advice..
Long story short back in 2018 my sister met a man in Toronto, Canada and ended up in a serious relationship with him after only talking for a few weeks.
Our entire family is from florida but she quickly decided to move up with him and lived there with him until 2024ish i think when she came back to the house. She had briefly mentioned him having a temper and that was enough for me and my mom in particular to give him a hard time while they were together for snapping at my sister.
Little did we know the man is a full blown psychopath. He essentially held my sister there against her will for all those years and threatened all of our lives every time she tried to leave. she had none of her own money and lacked even a citizenship so its a miracle she made it this far. He stole her things, murdered her cat, physically abused her on multiple occasions, just as horrible as it gets.
She moved back and thought she got rid of him but recently within the month he has started posting pictures of locations near our house and just today he showed up to the house driving a car with Ontario plates and was lurking near all of our cars. we called the police but he fled before they arrived and they essentially said there was nothing they could do. They even laughed when we tried explaining how serious this is.
my sister is TERRIFIED. the entire house is. He specifically hates me and my mother as well due to us never liking him in the past and has threatened my mom’s life several times. He IS 100% capable of murdering us. Due to him breaking and stealing several of my sister’s devices all she has as evidence is a few text messages threatening my mom. we cannot live peacefully knowing this man drove from Canada to Florida just for my sister. Im trying to look online for what i can do legally but i’m not getting clear results.
can anyone please help with some advice to get this man away from us or in jail?
Location: East Central Florida