Jason Derulo $680k Burglary Went Down While Employee Slept

Jason Derulo's home burglary is looking less like a random crime and more like the perps had some help ... TMZ has learned.

Law enforcement sources tell us ... the suspected burglars pried a door open to get into Derulo's pad last month, and made a beeline for his safe. We're told they beat the crap out of it, got it open and escaped -- all while one of JD's employees slept in the house.

Cops say about $600k in jewelry and about $80k in cash were taken. Now, to be fair, we're told Rip Van Winkle -- aka the employee -- was dozing pretty far away from the smashed safe. Jason's got a big crib.

Still, we're told cops suspect an inside job.