RENO, Nev. — An animal rights group is urging federal inspectors to fine Charles River Laboratories nearly $200,000 after the firm reported four more monkeys and other research animals died at its testing labs in Nevada and elsewhere since 2009.

Leaders of Stop Animal Exploitation Now say the most recent deaths demonstrate a continuing trend of negligence that has resulted in painful deaths of research animals. The group stepped up its scrutiny of Charles River in 2008 after a heating malfunction killed 32 monkeys in Sparks and another was boiled alive a year later in Reno when it was left in a cage in a washer.

The researcher paid a total of $14,500 in fines for the two incidents. The activists say puny penalties are why labs don’t take animal testing laws seriously.