The Possession of Dr. Diamond (2012)

From publisher blurb:

‘Doctor Diamond’ is a name known to most of the inhabitants of the City. He is an obsessed scientist overtaken by his theories of using diamonds and other crystals to break the dimensional barrier. Over the years this obsession has led him into several diamond and jewel heists attempting to get the materials he needs for his experiments. This almost always leads him back to jail at the minimum sentence for being just that pathetic.

All of that changed a week ago when Dr. Diamond succeeded in opening a doorway to another world. Zyr-Khan the Conqueror, a crystalline spider from the world on the “other side” leapt onto Dr. Diamond and instantly possessed him.

Since then the doctor’s reputation has changed. Dr. Diamond continues to plot ways to steal dimensional technology, but now there is a dark edge to the formerly soft spoken Doctor’s plots. In the last two heists two bystanders have been gravely wounded. Most troubling of all, the heists have been successful. Few suspect Zyr-Khan’s true plan is to create a dimensional bomb to send itself home, dragging the city with him in the process.

Events come to a head when the possessed Dr. Diamond breaks into the best equipped physics lab in the city, taking hostages in the process.