Putting it all together, I conclude that the Merced murders provide evidence against gun control laws, but weaker evidence than John Lott (and Vin Suprynowicz, from whom I think John got the original story) claim. Even without safe storage laws, the parents of small children–one of them was nine, I don’t know if she was the youngest–would be likely to keep firearms unloaded and on a high shelf or otherwise out of easy reach. Even if the Carpenter gun had been kept loaded and in easy reach, it isn’t clear whether Jessica could have gotten to it.
The case does not, contrary to John’s claim, provides clear evidence of media bias. The AP story did not remove evidence of the evils of gun control from the local story that was presumably its source, because the evidence wasn’t in the local paper until after the AP story went out. That conclusion might change if it turns out that there are later stories in the national media, based on later wire service versions, but I didn’t find any and would be mildly surprised to find national stories on a local killing still appearing three or four days after the event.