100℅ killer cobra.
I used to play it.
If you are Android user you can use.
CPC emu to play it supports.
https://play.google.com/store/apps/details?id=com.kokak.droidcpc
I guess you are looking for this game - "Profession Detective"
If this is not the game, here are a list of spooky Amstrad CPC games. Take a look and you may find the game you needed.
Ghosts N Goblins
Ghouls N Ghosts
Nighthunter
Cauldron series
Cauldron
Cauldron 2
Super Cauldron
Dracula
Chiller
Ghost Hunters
Werewolves Of London
Friday 13th
Zombi (Dawn Of The Dead)
Alien series
Alien
Aliens
Aliens (US Version)
Ghostbusters series
Ghostbusters
Ghostbusters II
The Real Ghostbusters
The Addams Family
Nightbreed
Arachnophobia
Nosferatu
The Rocky Horror Show
Predator
Predator 2
Gremlins
Gremlins2
Jaws
Frankenstein Jnr
Infernal Runner
Roland On The Ropes
Oh Mummy
Altered Beast
Space Gun
The Astonishing Adventures Of Mr Weem And The She Vampires
Striker In The Crypts Of Trogan
Myth
Dr Scrimes Spook School
Orion Prime