I'm sorry that it upsets you to hear that. To me, it's like going for a hike into the desert. It's dangerous to assume there will be public water fountains and restaurants, just like back home, so you don't need to bring any food or water.
I'm very sorry for this young man and his death, he certainly was innocent, posed no threat to anyone, and shouldn't have been killed.
I've never been to Urique, but I've explored it online as a possible destination, one stop on the very popular Copper Canyon railway trip. Expats live there and tourists safely visit, though it's way down at the bottom of the canyon, so off the beaten track. There's a famous marathon there that attracts 700 ultrarunners from around the world every year, who run through the wild hills on a predefined trail.
But, I have read many warnings to stick to the town and main roads, and take a local guide if you plan to hike outside those areas, otherwise you may run into people involved with the drug trade.
For many of us who travel to Mexico, the level of fear and outright paranoia some people have about the country is absurd - 40 million tourists visited in 2017: 40 million! So then some people assume all the warnings are pure paranoia, and the whole country is completely safe to explore. Some young travellers particularly enjoy boldly going where no tourist has gone before.
Between black and white are innumerable shades of gray. Unfortunately, it's now been confirmed those warnings about wandering outside Urique were accurate. The killer may have thought Patrick was a spy from the DEA or a rival gang, or something like that.
RIP Patrick.