I Need Help Finding This PS1 Game? Can Anyone Recognize It? It's A Horror Survival Game.?

Ok so I never owned a PS1 but my uncle did and I'll do my best to describe it. I tried searching for a list of horror survival games but didn't find one that matched my memory (although I didn't search all of the titles currently). It is NOT: Silent Hill, Resident Evil, Clock Tower, Dino Crisis, Parasite Evil, Alone in the Dark, Count Down: Vampires, Echo Night, Chaos Break or Evil Dead, to name a few. Here's the description of the game I'm thinking of:

It starts off very slow (the game builds). You're with a team of 3 other people, so 4 max I believe. You have to put a name for your character in when you start. I think you start off in a business building, potentially a lab. Essentially, your job is to investigate some sketchy stuff (mutants I think?) that has gone wrong. Eventually I believe the rest of your team disappears after searching for the disturbances that your team has been sent to report on and uncover, leaving just the main player (you). The game eventually builds into a more horror suspenseful/tense atmosphere. What I remember is that when walking up or down a set of stairs, there's a short cut scene that shows a set of wooden steps surrounded by a black background (again, for suspense), with creepy music playing in the background echoed by footsteps. Eventually, you'll come across an area in the game where there is a character who my cousins and uncle called "the frog man." And there's something about a safe house too where the "frog man" can't attack you.