We don't know if it was a ricochet, and if the window was broken he may not have known it was a pellet. Some of the better air rifles can shoot a pellet at over 1000 fps.
My son gave me a birthday present of a really nice .22 pellet rifle. I set up a very protected shooting range which included a multilayer carpet backup cooler box in my large backyard. I intentionally set the target trap close to ground level at my 25 yd sighting distance and in front of a 6ft fence. I made sure by sighting that the trap was not in line with any houses. I was zeroing pellets that were chronographed at 850 to 1200 ft/sec. I checked the laws and even called the police dept. to tell them what I was planning. No problem as long as pellets stayed on my property. I was enjoying shooting my new rifle when the police came to the door. A neighbor had reported I was shooting at and killing birds. An absolute false claim. I had a good chat with the officers, a seasoned lady cop and a punk cadet cop, and told them my next shooting would be on some mountain property. It is the neighbor who pounds on his house at any time of the day and the young have-a- badge cop who need some learning.