Slesin
Have you looked at this town?
en.wikipedia.org/wiki/%C5%9Alesin
Problem is that without further information it is going to be difficult to help you.
As regards the surname, all I could find is this:-
" Antecki is a variation of the name Anthony , one of the most common names, derived from Latin Antonius , an ancient Roman family name of unknown etymology. Antaki may be a variation as well"