The above comment is correct. People who are psychologists tend to have a PhD or PsyD and not a medical degree and therefore cannot administer medication unless they have a secondary degree. People with a medical degree who specialize in forensic populations would be a forensic psychiatrist, not a forensic psychologist.
I believe this depends on their licensure. A forensic psychologist who holds a PhD or PsyD cannot administer medications in most states, however, a forensic psychologists (really a psychiatrist) with their MD or DO can administer medications.