Maybe he killed em outside the city limits or something, I don't know. He was never convicted of killing anyone but was suspected in somewhere around 25 hits. He was an out and out psychopath.

This is from a Chicago newspaper called the Beachwood Reporter:

Accardo/Roemer:

[Spilotro] shaped things up by killing five people as soon as he arrived.

*

Cullotta/Griffin & Cullotta:

In Tony's first three years in Vegas, more gangland-style murders were committed there than in the previous 25 years combined.

He also ordered Frank Cullotta to kill at least one person in Vegas but again maybe it was outside the city limits or something, I don't know.

You're right, though, he ended up getting murdered for bringing too much heat down on Vegas and killing the cash cow. So I wouldn't be surprised if his excessive violence factored into the Outfit's decision to whack him.

After they killed him they replaced him in Vegas with Don Angellini who was apparently the exact opposite: Smart, nonviolent.