Extra men for murder inquiry MELBOURNE, Monday. — Another four Melbourne detectives will go to Shepparton this week to join investigations into the murders of Abina Madill, 16, and Gary Hey wood, 18. Three members of the Melbourne Homicide Squad already are working with Shepparton CIB on the case. The decision to strengthen the team was made today at a conference of 15 detectives at police headquarters. The conference was attended by the Chief of the Shepparton Police District, Insp J. Matthews, the detective leading the inqujry. Sen-Det P. Parkinson, and 13 members of the Homicide Squad. The conference discussed progress made during the inquiry and went through some of 1,600 typewritten pages compiled during investigations. The chief of the Homicide Squad, Det-Insp F. Holland, said after the conference that police believed a person who had written two anonymous letters might be able to help them. The person sent a letter to police and to the father of the dead girl. The letters said the murderer was employed in a Government department in Shepparton. Det-lnsp Holland appealed for the writer of the letters to come forward. "We would give the person full protection and his identity would remain a secret," he said.