Awful to hear that one's died, hope the other three are okay.
I've seen speculation that rather than a misguided rewilding attempt that the person responsible may have had the lynx as unlicensed pets, but became unable to manage them, feared prosecution if they surrendered them to a sanctuary or zoo, so dumped them then gave the police an anonymous tip off they'd been released, which is why the police were taking it so seriously from the start.
Pure speculation obviously, but you'd have thought even the most impatient rewilder would understand the importance of making sure the animals were ready, so might have something to it. Though should never underestimate human stupidity, I suppose.