None of us know if either of them were psychopaths. Psychopathy can only be diagnosed with a brain scan. Also, psychopathy is a spectrum, not a clearly defined thing. There's also sociopathy which is mainly a result of environment, but can result in similar consequences.
Additionally, thousands of years of human history shows that ordinary non-psychopaths have the capacity to commit all sorts of atrocities against random, innocent people. And not everyone who is a psychopath commits violent crimes.
Also:
Why Mass Killers Aren't Necessarily Psychopaths
Additionally, any researcher in the field of psychology or criminology can tell you that environmental factors influence development. Even if someone is born a psychopath, that doesn't make them "destined to kill." And there is a clear correlation between people who commit random acts of violence, and having a history of abuse.
Op-Ed: We have studied every mass shooting since 1966. Here's what we've learned about the shooters
"First, the
vast majority of mass shooters in our study experienced early childhood trauma and exposure to violence at a young age. The nature of their exposure included parental suicide, physical or sexual abuse, neglect, domestic violence, and/or severe bullying. The trauma was often a precursor to mental health concerns, including depression, anxiety, thought disorders or suicidality."
The incidence of child abuse in serial killers
"Abuse was categorized into physical abuse, sexual abuse, psychological abuse, and neglect and was then compared to societal norms from 2001. Abuse of all types excluding neglect was significantly higher in the serial killer population."
(Yes, I know that Kam and Bryer were spree killers, but spree killings aren't as common so there isn't as much research done on them...either way it all falls under the category of random violence.)