Nonmeasurable subgroups of compact groups
  In 1985 S.~Saeki and K.~Stromberg published the following question: {\it Does every infinite compact group have a subgroup which is not Haar measurable?} An affirmative answer is given for all compact groups with the exception of some metric profinite groups known as strongly complete. In this spirit it is also shown that every compact group contains a non-Borel subgroup. 
Salvador Hern\'andez, Karl H. Hofmann, and Sidney A. Morris
math.GR