I just want to know what happened. I just want to know. I just want to know like after 15 years of imagining all these horrific things. I just want to know. I just want to know truth. That's it.

All Natalia St. Louis wants is the truth about what happened to her father.

The details of that July afternoon in 2006 don't make any sense. It was

labeled a medical call, an apparent seizure, but the autopsy report and blood evidence at the scene points to something much more violent than that.

But over 15 years later, Sean O'Brien's case is still labeled a suspicious death.

She's been told to keep quiet, but if she's not asking questions, chasing down leads,

and talking about her father's case, who will?

I'm Kylie Lowe and this is the case of Sean O'Brien,

told by his daughter Natalia St. Louis on Dark Down East. When Natalia St Louis was a kid growing up in Cranston, Rhode Island, she didn't really notice anything was missing in her life.

She was close with her mother, Amy, and had a big Italian family who supported and celebrated everything she did.

My mom always did the best by me.

My whole family always did best by me.

I grew up Italian so it was like you know Sunday dinners were our

thing and going to church on Sunday mornings and I loved school I loved going to school I

loved playing school I always wanted to be a teacher. So I think I had a really good childhood, I think despite, I don't remember ever realizing like, oh, I don't have a dad. Like I don't, it didn't dawn on me that there was anything

a miss, like it didn't dawn on me that my dad wasn't in my life at the time.

Her parents were together when Natalia was born, but they split when she was about two years old.

For seven years, it was just mother and daughter. They were best friends.

Nothing was lacking. Natalia was happy. It wasn't until her parents

reconnected when she was nine years old that she realized just how special dads

can be.

So my mom and dad finally reconnected

...