A useful article on what a "psycho" (used here as an abbreviation for psychopath) actually is

http://www.psychiatrictimes.com/dsm-iv/content/article/10168/54831

The whole thing's pretty interesting but here's the relevant snip for
those who aren't interested in the details.

"
Most psychopaths (with the exception of those who somehow manage to plow
their way through life without coming into formal or prolonged contact
with the criminal justice system) meet the criteria for ASPD, but most
individuals with ASPD are not psychopaths. Further, ASPD is very common
in criminal populations, and those with the disorder are heterogeneous
with respect to personality, attitudes and motivations for engaging in
criminal behavior.
"