Commonwealth has the burden at the preliminary hearing to establish a prima facie case that crime has been committed and that accused probably committed it.  The Commonwealth does not have to prove the accused’s guilt beyond a reasonable doubt; to meet its burden at preliminary hearing, Commonwealth must present evidence with regard to each material element of charge and establish sufficient probable cause to warrant belief that accused committed offense.   While the Commonwealth need not prove the elements of the crime beyond a reasonable doubt at a preliminary hearing, the prima facie standard requires evidence of the existence of each and every element of the crime charged lest the jury be left to speculate regarding an element.