Isn't that the suffix for a Chinese name? :)
Sometimes it’s borg,(meaning “town”) or -man, as in Silverman,or Goldman.
Other aliases include uses of a man’s English name as in Roberts, Williams, or Williamson or Robertson.
They are basically stage names to hide their true identity.
To be fair, this does NOT mean that all those with surnames like this are criminals.
Take for example Robert Williams. Was he a criminal? Who knows? But was this his real name?