Are turboprops less safe then jets?
There is no hard answer to this and it should always be looked at carefully as its dangerous to compare these things. The factors vary widely and a clear cut comparison is generally hard. Twin Turbo-Props may have a lower celling than your average regional jet, they often fly shorter routes and see more cycles compared to their total hourly lifetime, some turbo-props are even in reach of private pilots which puts them in a different operational situation all together but will be lumped in on the statistics.   

The most comprehensive study I can find on the topic, and one I feel breaks it down nicely, is this one from NASA 


  Differences in Characteristics of Aviation Accidents during 1993-2012
  Based on Aircraft Type


Im going to refrain from quoting to much directly as its all relevant and a fairly short 20 page read. The table that seems to sum it up best is the following (refer to study for table explanation):





A bit of a tangent but related, here is a nice article from AOPA comparing the data for Small Jets VS Turbo Props operated under part 91