When I've been at a lost as to how to locate a relative who I know little about, I check out Ancestry.com family trees, to see if anyone else includes the person that I'm interested in. With Abraham Weisfeld having so many children, it's likely there are grandchildren or great grandchildren who have put up trees on Ancestry that you could consult to get clues as to the life story of your grandfather (though the clues have to be verified).
I would think that a killing in 1905 would have been covered in the newspapers, so checking those out might yield something.
Lock/Lak/Lok and Kalon in Zagare/Joniskis/Gruzdziai, Lithuania
Trisinsky/Trushinsky/Sturisky and Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Poland/Lithuania
Gutman/Goodman in Czestochowa, Poland
Lavine/Lewin/Levin in Trenton, New Jersey and Lida/Vilna gub., Belarus