Whoever wrote that headline should have their credentials revoked.............
I’m not an English major - and I can see how the headline might seem ambiguous, but had it been about the death of the teen, it should have been punctuated thusly:
Teen, arrested for murder of California woman, fatally stabbed while hiking.
It reads like the teen who was arrested got fatally stabbed while hiking.
How about instead: Teen Arrested For Murder in California Hiker Stabbing
Gets rid of the word “fatally” but that’s clearly indicated in the murder charge.