Los Angeles, California (CNN) -- The FBI and University of California at Los Angeles police are investigating a new round of threats from anti-animal research activists who claimed to have sent AIDS-tainted razor blades and a threatening message to a research professor, a university spokesman said Tuesday.
The university said law enforcement officials confirmed that UCLA neuroscientist David Jentsch received a package at his home containing razor blades and a threatening note.
The North American Animal Liberation Press Office posted an unsigned communique on its website from a group calling itself "The Justice Department at UCLA," claiming its members sent the razor blades to Jentsch because he uses primates for government-funded testing of drug addiction.
"He has no business addicting primates to phencyclidine known on the streets as PCP and other street drugs using grant money from the federal government," said the statement issued Tuesday by the activist group.
Since 2006, other anonymous activists claimed responsibility for at least 11 acts of sabotage, vandalism, criminal damage and firebombing against UCLA faculty or property, either on and off campus, university officials said.
In March 2009, activists seeking to stop the use of animals in research claimed to set fire to Jentsch's vehicle parked overnight outside his home.
Jentsch, a professor of psychology, psychiatry and biobehavioral sciences, uses vervet monkeys in his research into the biochemical processes that contribute to methamphetamine addiction and tobacco dependence in teenagers, and the cognitive disabilities affecting schizophrenia patients, according to the university.
Much of Jentsch's work is funded by the National Institutes of Health, university officials said.
"Responsible use of animals in research aimed at improving the health and welfare of the mentally ill is the right thing to do, and we will continue because we have a moral responsibility to society to use our skills for the betterment of the world," Jentsch said in a statement.
In a phone interview with CNN, Jentsch said the activists have been "using various tactics to get at me."
"They started with incinerating my car," he said. "They have participated in monthly demonstrations outside of my house. Usually the threats are general, this one was very specific. "They said they were going to cut my throat, and they named one of my students.
"I'm not afraid. I'm angry. It's so ridiculous in our society that people do this just because they don't like what you do," he added.
Jentsch provided an account of the threat.
"About a week ago I was going through my mail in my kitchen and I opened a letter and razor blades spilled out on the floor. It was the first sign something was nefarious," he said. "The letter inside contained quite specific and heinous acts of violence to kill me."
He said the letter was signed by the Justice Department, which he described as a group "loosely aligned with the Animal Liberation Front."
"The major reason [no one has been arrested] is because the Animal Liberation Front has no official membership. Their spokesman calls from underground and claims to not know any of its members," Jentsch said.
Jerry Vlasak, an animal rights activist, said he does not know who targeted Jentsch but he says he understands why the researcher was targeted.
"He does not have the right to go home to feel at ease. Try to look at it from the perspective of the innocent beings that he is doing this to," Vlasak said.
Vlasak says he is a medical doctor who also used to do animal research but stopped because he felt it was incredibly torturous to animals.
"He has refused to debate with me and other doctors. He has spoken out against animal activists. So he has basically made himself an even bigger target, by saying not only am I going to continue torturing animals but I am flipping the bird to all these animal rights activist that want to stop me," Vlasak said.
University spokesman Phil Hampton condemned the threats.
"What's happened here recently is only the recent manifestation of a pattern of reprehensible, repugnant criminal activity directed at UCLA researchers," Hampton said. "UCLA is committed to conducting research that helps us to understand better the human body and is making important steps and strides to new diagnoses, treatments and cures to a wide variety of ailments such as Parkinson's (disease) and cancer."
CNN's Nick Valencia contributed to this report.