Holmes was taking sertraline, a drug which is in a class that is problematic, to say the least. Some people appear to get violent with Selective Serotonin Reuptake Inhibitors (SSRIs). Some soon after they start the drug, or increase the dose or add another drug that increases serotonin in the blood. It's called serotonin syndrome. Others stopped it too quickly. They get what's called SSRI withdrawal syndrome or SSRI discontinuation syndrome.
SSRI Stories - Antidepressant Nightmares
A lot of primary care docs write scripts for these meds, but many are unaware of either serotonin syndrome or SSRI withdrawal syndrome.