Yandamuri, 28, could be sentenced to death if a jury convicts him of first-degree murder charges in the kidnapping and killing of 10-month-old Saanvi Venna and the slaying of the child's grandmother, Satyavathi Venna, 61, in October 2012.
Authorities say Yandamuri entered the Vennas' apartment at the Marquis Apartments in King of Prussia, where Yandamuri and the Vennas lived. The slayings, they say, were part of a botched plot by Yandamuri to kidnap the child and get ransom money to pay gambling debts.
Yandamuri denies that and says police coerced him into confessing to the crimes.
O'Neill's decision came after Deputy District Attorney Samantha Cauffman invoked the pain of the victims' family and urged the judge to let the trial date stand. The case already has been marked by delays, Cauffman said, due to factors including Yandamuri's discontent with his court-appointed lawyers.
"You cannot imagine how hard that is for them," Cauffman said of the proceedings' pace.
O'Neill said he was sympathetic, but "I have to be true to the defendant's right to defend himself and prepare for trial."
Yandamuri still will have an attorney represent him in the penalty phase if he is convicted of the murder charges.