Investigation missions are side missions in Grand Theft Auto: Angels of Police. They are unlocked after completing the mission "Denieng the Dead".
Investigation is where Natalia(herself or with backup) must retrieve and find unregistered weaponry in possession of mafias, cartels, or just random people. There are 50 missions in all.
After completing 10 investigations up to 50, weapons will spawn in Natalia's house:
- 10: A Stun Baton spawns in Natalia's bedroom
- 20: A Laser Sight Pistol spawns in Natalia's bathroom
- 30: A Pump Shotgun spawns in Natalia's living room
- 40: A Laser Sight SMG spawns in Natalia's basement
- 50: A Carbine Rifle spawns in Natalia's kitchen