From the Wikipedia article ThaiWx so kindly posted (for the doubters, amateur physics experts and self proclaimed ballisticians):

"Firearms expert Julian Hatcher studied falling bullets and found that .30 caliber rounds reach terminal velocities of 300 feet per second (90 m/s) and larger .50 caliber bullets have a terminal velocity of 500 feet per second (150 m/s).^[8] A bullet traveling at only 150 feet per second (46 m/s) to 170 feet per second (52 m/s) can penetrate human skin,^[9] and at less than 200 feet per second (60 m/s) it can penetrate the skull.^[10] A bullet that does not penetrate the skull may still result in an intracranial injury.^[11]"

Yeah nah, Ballistics is what I do for a living (albeit stopping projectiles with hard armour), im calling bullshit as well.

Sounds like the experience is working against you. Fired at an angle, easily doable.

It came through the roof, then through the ceiling then bounced off her cheek, it was a 9mm projectile..... I'm confident in my call.

Yeah nah, Ballistics is what I do for a living (albeit stopping projectiles with hard armour), im calling bullshit as well.

Sounds like the experience is working against you. Fired at an angle, easily doable.

It came through the roof, then through the ceiling then bounced off her cheek, it was a 9mm projectile..... I'm confident in my call.

Hey, here's an idea! Though the OP seemed a sincere and credible poster; given your expertise on the subject; why don't you make an offer to meet him and his neighbour? You could challenge them to pay you 10k Baht if they are making this story up and in kind you could offer 10k Baht if it proves to be true. That would go a long way towards fixing the unfortunate lady's roof.