The 42-year old victim recently came from Florida to help the child's mother, who is estranged from Evans. He showed up at the house on Thursday night while Joan Whitfield, 47, was at work.
The shootings late Thursday occurred about the same time as an over-the-phone argument between Evans and his wife, Mount Vernon police Chief Barbara Duncan said. She would not disclose details of the argument.
The argument was troubling enough that the wife, a registered nurse working at a New York City hospital, called police at 10:36 p.m. and asked them to go to the house.
As officers arrived at the two-story brick house on Ellwood Avenue, 50-year-old Evans walked out and surrendered, the police chief said.
Inside, officers found the child and the baby sitter in separate rooms on the second floor, Duncan said. The child, Ayana Evans, had been shot in the torso; the baby sitter, Lorna Williams, was shot in the side of the head.
Police also found a handgun, which was being tested to see if it was used in the killings.
Duncan said she did not know if the shootings had occurred before, during or after the phone argument. The mother, Joan Whitfield, did not hear gunshots, she said.
Whitfield is a member of the U.S. military and recently served in the Middle East, the police chief said. She and her daughter moved to Mount Vernon several months ago. Duncan said the husband's most recent address was in Brooklyn and he apparently did not live with his family. She did not know if he was employed.
The chief said police were unaware of any divorce or separation proceedings under way or any orders of protection.
Evans was arraigned Friday on a count of first-degree murder and ordered held for a hearing Thursday. No plea was entered. His lawyer, Claire Degnan, did not immediately return a phone call seeking comment.
The police chief said the mother arrived at the house after calling police; her daughter had been taken to Mount Vernon Hospital, where she was pronounced dead. The sitter was dead at the scene, Duncan said.
Mount Vernon Mayor Clinton Young, who lives a few houses away, was at the scene Thursday night.
"The mother was extremely emotional," he said Friday. "She lost her child."
Ellwood Avenue is a tree-lined, upper-middle-class street of neat private homes about 15 miles north of midtown Manhattan.
"My entire neighborhood is in shock," the mayor said. "I remember seeing this little girl riding her bicycle and walking to school with her friends."
Grief counseling was arranged at the girl's elementary school.
Tobie Tripodi, who lives across the street from the scene, said she was awakened Thursday night by the police activity. She said the girl and her family had recently moved in and "seemed like a quiet family."
She said she had waved to the child on her way to school.
"I'm horrified by it," Tripodi said of the killing. "A child? Come on. The most innocent among us."