Suspicious letters to L.A. Times and Palm Desert's McCallum Theatre probed

Laura Eimiller, a spokeswoman for the FBI in Los Angeles, said the Joint Terrorism Task Force is investigating the letters, but said the granular substance in the letters tested negative for hazardous biological or chemical materials.

"Further testing will be conducted, but that is routine," Eimiller said.

Employees of the McCallum Theatre in Palm Desert discovered the suspicious letter Friday morning and notified the Riverside County Sheriff's Department, according to Deputy Herlinda Valenzuela. The theater's employees were evacuated while a hazardous-materials team secured the letter and forwarded it to the FBI.

Friday's scheduled performance by singer Boz Scaggs was canceled. Comedian Bill Maher is scheduled to perform there Saturday evening.

A similar letter delivered to The Times on Friday was also being investigated.

scott.glover@latimes.com