The Scream Museum

Description for THE SCREAM MUSEUM by Paul Zindel:

P.C. Hawke and his partner-in-sleuthing, Mackenzie Riggs, are shocked to learn that their friend, Tom, a custodian, is accused of murdering the chief biologist at the Museum of Natural History. As P.C. and Mackenzie dig deeper into the strange story, they discover a stolen world-famous necklace, an anthropologist trained in Indonesian medicine and hypnosis, and a fat, hairy tarantula named Aristotle.

This is #1 in P C Hawke Mysteries.