Casmir Weronecki looking for info on him

I am new to this forum, but i'm trying to find out info on a relative from Poland.
He is my Great Grandmother's brother. (my great great uncle)
We just received a family tree and have a disturbing relative on it!
This is what it says (all names are spelled exactly as on the family tree, not sure if they are actually the correct spelling or not) Here it goes.....

Casmir Weronecki DOB unknown probally about 1888 or so.
We have no date information on him. He spent 20 years in prison chained to a wall. That is where he died. He was married but we have no information on her. The reason he was sent to prison is that he cut off her head with an ax.

The only town/county it says is Mielec, not sure if Casmir is from there or not.

My neighbor is from Poland and says he's heard of this man. He was not in an actual prison, but in the "dungeon" of a castle. He actually killed his wife;s family too. Not sure if this is true. He also says that there is a book written with Casmir's info in it. Has anyone ever heard of it, or know the name of the book?
Any info would be great! IF this is true, he is the only murderer in the family, the rest of us are just fine, and as normal as can be expected. WE are just trying to find out if this is true or not.
Please help with info. We are very curious!! thank you!