The colleague in question is in his 60's; we work for the same company but we don't work together as such.
He apparently told someone, who told me that on occasion he has hit his wife when she wouldn't do what he wanted. 
I have never met his wife, nor am I ever likely to.
My problem is that if it is true then I cannot just stand by and let it happen. On the other hand I do not know for sure that it IS true, as it is just hear-say at the moment.
Is there anything I can do?