Responding to you but multiple people have mentioned silencers. They are rarely used in crimes, and up until recently (law went into effect on January, 1) were a complete pain to get. They required a $200 tax stamp, and the wait was many months until the paperwork was processed.
They also don't function at all like they do in that movies (that high-pitched "pew pew" sound.
Here's a chart with the decibel level of a 9mm handgun, without a suppressor and with one.
I think people just didn't hear it (it would be super loud inside the house but not outside), or they wrote it off.
| ~157–167 dB | ~125–134 dB | ~30–34 dB |