E34 Is unlocking itself

[kortz83 13]

Hey there,

I go to work lock my car up and i come back about 8 hours later and the doors are unlocked but if you open the doors the alarm will go of it's happened 3 days in a row now, I'm just wondering if anyone would have any idea of what this could be? It's a 1989 525i

Thanks

[BM WORLD 1283]

would guess a faulty locking actuator , but which one ?? , is there a lazy door (slow) lock etc when you lock the car ??