WATERVILLE, Maine — Relatives of a woman whose toddler is the subject of an intensive search said Monday that they feared for the girl's safety while she was staying with her father, who was caring for the child when she disappeared.

Twenty-month-old Ayla Reynolds was reported missing Saturday morning by her father, Justin DiPietro, who called police to say she was not in her bed in Waterville.

Whitney Raynor, her mother's stepsister, said Monday that welfare agents had placed Ayla with her father in November while the mother was in rehab for substance abuse. The girl had bruises after being in her father's care, Raynor said, in addition to a broken arm three weeks ago.

"Our biggest fear is that he lost his temper and something happened. We're trying not to think about that, but in the back of our minds it's our biggest fear," Raynor said from Portland, where Ayla's mother, Trista Reynolds, lives.

Waterville Police Chief Joseph Massey has said the broken arm was from an accidental fall. The girl was last seen Friday night 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.

Spokesman Steve McCausland of the Maine Department of Public Safety said police learned of the girl's cast on her arm from either DiPietro or guests at his home Friday night. A message left with Massey wasn't immediately returned.

A phone number for the father couldn't immediately be located. Police outside his house Monday in Waterville said he was not there, and the girl's disappearance remains a missing-persons case. Two cars were towed Monday from near DiPietro's house, but police would not comment on who owned them or why they were taken away.

Massey said every lead reported by the public is being followed in hopes of locating the child.

"We are approaching this with every possible thought and angle in mind. It is currently a very open case," Massey said at a briefing. He said about 75 officers, including game wardens specially trained in search and rescue, were working on the case.

As the search entered its third day, a Maine Warden Service plane circled overhead, wardens searched a stream near the father's house and residents joined in canvassing the neighborhood for any signs of Ayla.

Wardens focused most of their efforts Monday on Messalonskee Stream, and the FBI and Maine State Police were helping Waterville police investigate, McCausland said.

The stream meanders through Waterville, a city of about 16,000 located 20 miles north of Augusta.

Many residents joined in the search. Carrie Harvey, who lives nearby, found a sippy cup lid near the neighborhood and turned it over to a warden.

"It's sad. Christmas is right around the corner. My heart cries out for that lady," Harvey, a mother of five, said of Ayla's mother.

Reynolds, who also has a 7-month-old baby, is now doing better after rehab, and she went to court Thursday to regain sole custody of Ayla, Raynor said. DiPietro didn't know about the court filing, she said.

Reynolds told ABC's "Good Morning America" on Monday that she and the father have been unable to get along in the last few weeks.

"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 is where she is," she said.

Investigators interviewed the parents, as well as other family members, and they were cooperative, Massey said.

The father moved four to six weeks ago to his childhood home on Violette Street in a tidy neighborhood of small ranch houses built after World War II, a neighbor said. A few blocks away is a park, alongside the stream.

A state police evidence van was parked outside DiPietro's gray, vinyl-sided bungalow on Monday, and two state troopers were stationed outside.

"It's just so sad, so sad. I hope we end up with a live child," said Ellen Paul, a retired Colby College employee who lives across the street from DiPietro's home. "I'm heartbroken for anybody to go through that kind of pain."

Associated Press reporter David Sharp in Portland, Maine, contributed to this report.