Leslie Ross, 66, of Dromore, a market town 19 miles southwest of Belfast, said little during an appearance in magistrate's court in Armagh, the Belfast Telegraph reported. He said he understood the charges.
A judge ordered that Ross remain in custody.
Ross was arrested Tuesday on suspicion of killing Michelle Bickerstaff, 47, in April 2012, Margaret Weise, 50, in 2007 and Lily McKee, 52, in 2002. Investigators had said Thursday he would be charged with killing Bickerstaff and Weise, while the file on McKee's death would be forwarded to the director of public prosecutions.
Conleth Downey, Ross's solicitor, told the court his client maintained his innocence under lengthy police questioning. The lawyer said Ross' house has been vandalized since his arrest.
"In essence, Mr. Ross has indicated that he categorically and vehemently denies all allegations of wrongdoing," Downey said after the hearing.
The sex charges were only revealed during the court hearing. Ross was detained for questioning after Bickerstaff's death and released with no charges.
Relatives of Ross' alleged victims packed the gallery during the hearing. They refused to talk to reporters afterward.
Ross is scheduled to be back in court in September.