This doesn't shock me... just anger and sadness.
I would start looking for a young male and his friends
Most likely poor lacking education and out of work
Or working -but at a low wage menial job.
They would also be local to the area and had been to the site before.
Eric,
The person(s) that did this knew the prized individuals (including the gravid females)
what would cause the greatest harm and loss to the restoration project.
another story link 1, and two
I see the motivation as someone being spiteful hate that the "dumb lizards"
that get more attention and money than what they do from the rich tourists.
The simple fact that they were stomped, stabbed and torn apart while still alive
tells much about the type of anger the perp has for himself and others.
(blood smeared on the walls of the enclosure...)
IF the local cops are motivated... the perp(s) will get caught
If it's the types that I imagine the are... they'll be talking to their friends
or the friends already involved will talk among themselves.
Someone will turn them in for the reward (that's building over 10,000 £ GBP / $20K USD right now).