The mother of a missing 20-month-old girl filed paperwork seeking sole custody a day before the girl disappeared from the father's home, and she said she wants answers from "the last man to see my daughter."

Trista Reynolds reportedly said she and Ayla Reynold's father have been unable to get along in the last few weeks. She said she didn't tell the father, Justin DiPietro, that she'd filed the court paperwork Thursday.

"I've had no contact with him; he's had no contact with me. All I know is he's the last man to see my daughter, and all I want to know where she is," she told ABC's "Good Morning America" on Monday.

Investigators on Monday searched the Messalonskee Stream in Waterville, not far from her father's home. 

Over the weekend, police appealed for the public's help in finding the youngster after DiPietro called police Saturday morning to report that his daughter was not in her bed and couldn't be found. Ayla was last seen Friday night.

Ayla is described as 2-feet-9 inches tall, weighing 30 pounds. She has blonde hair. She was last seen wearing green one-piece pajamas with polka dots and the words "Daddy's Princess" on them. She had a soft cast on her left arm. Waterville Police Chief Joseph Massey said Ayla broke her arm in a fall three weeks ago.

Massey said investigators interviewed the father, who lives in Waterville, and the mother, who lives in Portland, as well as other family members. He said they all were cooperative.

Authorities interviewed neighbors and searched the area Saturday and Sunday. They also used a search dog at the girl's house to make sure she was not hidden in a closet or some other small space, Massey said.

The police chief said all possibilities were being investigated, including abduction.

"Everything is open. Everything is on the table," he said. "We have not uncovered any information that has sent us in any direction."

Police said early Monday that a press conference is scheduled for 2 p.m. 

Waterville is about 20 miles north of Augusta.

Police are urging anyone with information on Ayla's whereabouts to call them at 207-680-4700.

The Associated Press contributed to this report.