  The Noether-Horikawa surfaces are the minimal surfaces S with K^2=2p_g-4. For
8 | K^2 they belong to two families of respective type C and N (connected,
resp. non connected branch locus for the canonical map). For 16 | K^2 the two
types are homeomorphic. Ulf Persson constructed surfaces of type N with a
maximally singular canonical model X, whose topology encodes information on the
differentiable structure of S. A similar analysis was done by the first author
for type C. In this paper we study the genus 2 fibration on X and, in
particular, our main result is (X^# being the nonsingular locus of X)
\pi_1(X^#)= Z_4 x Z_4 if 8 | K^2 but 16 does not | K^2 \pi_1(X^#)= Z_4 x Z_2 if
16 | K^2.
