D. Cooper et D. Long, A KLEINIAN GROUP WITH CONTRACTILE QUOTIENT NOT SIMPLY CONNECTED AT INFINITY, Commentarii mathematici helvetici, 71(1), 1996, pp. 41-59
We give an example of a co-compact Kleinian group Gamma which contains
a subgroup Gamma(0) having the property that H-3/Gamma(0) is contract
ible but not simply connected at infinity.