Unfortunately, crucial details such as those pertaining to your question were omitted from this woefully short news story. It is said that the potato was found under the woman's body and so I'm guessing that she was hit with something else, because for her to fall on the object that was used to hit her might be a somewhat difficult maneuver, although that's just my idle musing.
I would imagine also that for an otherwise healthy person to be injured so badly as to cause her to fall unconscious, as is suggested by the story, it would take a fair amount of force. Such force would, I'm guessing, most likely render a typical potato into a more or less mashed state.
Those were two different stories. The subject of the main story evidently never pulled the trigger on the potato-silenced gun, but instead beat a woman with something else.
The 2nd story is told about a man who did try to use a potato to silence his gun, which he did shoot, and which potato ended up being found underneath the victim who was shot.
It did not say in what condition the potato was found. Seems like it would have been blown to smithereens, but maybe that's the gratuitous violence we're not supposed to reference.