Have any of you been following this story? At first, before paying attention to the details, I wondered about familicide.

https://www.sfchronicle.com/bayarea/article/Not-one-clue-The-mystery-is-only-deepening-16401921.php

After reading the article and looking at a topo map, I came to this conclusion...

These are heat-related deaths until proven otherwise. They went on a 7+ mile dayhike with a 1 year old who may have been the first to begin showing signs of heat stress. They may have known of the algae issue (trailhead signs, online/tv news, since they were locals) and only took/used their own water causing further problems if they underestimated how much was needed for a family of four (3 humans, 1 dog) in those conditions. Once down at the river there is a 3.3 mile 2,500 ft climb back up. The temps were up to 109 F. There is said to be not much shade after the 2018 fire. They had little remaining water when found only halfway up the climb. Toxicology is pending.