WATERVILLE, Maine — The search for 20-month-old Ayla Reynolds continued on Monday as the Maine Warden Service, state and local police investigators and Federal Bureau of Investigation agents combed the area to find the girl who was last seen Friday in her father’s home on Violette Avenue.

The warden service began searching the surface and banks of Messalonskee Stream by plane, boat and foot on Monday, expanding the search area from the weekend, Waterville Police Chief Joseph Massey said during a press conference Monday afternoon.

“It was logical considering [the stream’s] proximity to Violette Ave.,” Massey said, adding that the stream is just one-eighth of a mile from the home.

Massey said 75 investigators are assigned to the case, including 25 from the warden service who pushed their search to the stream.

“It’s very important for us to be methodical, it’s very important for us to follow every single lead,” he said. Massey added that all groups involved in the search would continue to “pour our resources in.”

Massey wouldn’t say whether police believed Ayla had been taken from the Violette Avenue home, wandered off into the cold or something else happened.

“The focus, obviously, is to bring Ayla home,” Massey said.

Police asked for the public’s help in finding the girl over the weekend after her father, Justin DiPietro, reported her missing. Ayla last was seen in her bed at DiPietro’s home Friday night.

Ayla is blond and 2 feet 9 inches tall. She last was seen wearing green pajamas with polka dots and the words “Daddy’s Princess” on them. She had a soft cast on her left arm because she broke her arm in a fall three weeks ago, according to Massey.

Police interviewed Ayla’s mother, Trista Reynolds, and DiPietro, as well as other family members over the weekend, and all were cooperative, Massey said.

Ayla’s parents are separated. DiPietro lives in Waterville and Reynolds lives in Portland. The two have struggled to get along, and Reynolds told ABC’s “Good Morning America” she filed paperwork on Dec. 15 to obtain full custody of Ayla.

“I’ve had no contact with [DiPietro]; 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,” Reynolds said Monday.

Among the leads police are investigating is the claim by a neighbor that a vehicle pulled up to DiPietro’s home late Friday night for a brief time, Massey said.

Investigators had two vehicles towed from the Waterville home on Monday. Massey wouldn’t say why the vehicles were taken but said it was related to the investigation. Family members have not been allowed to stay in the home since the investigation started, he said.

Police did not call for an Amber Alert during the search for Ayla because they weren’t informed that she was missing until nearly 9 a.m. Saturday, around 10 hours after she last was seen in her bedroom. The Amber Alert Program is a voluntary partnership among law enforcement agencies, broadcasters, transportation agencies and the wireless industry to activate an urgent bulletin in the most serious child abduction cases, according to the U.S. Department of Justice website. The goal of an Amber Alert is to instantly galvanize a community to assist in the search for the missing child.

The Waterville Police Department, Maine State Police, Maine Warden Service and the FBI are collaborating in the search for Ayla, according to Massey. Investigators from each agency met in the Waterville City Council chambers on Monday morning to organize their search efforts, he said.

“Each of these agencies bring a unique expertise to finding missing children,” Massey said.

Cases of children disappearing from their homes in apparent abductions are few and far between, state police spokesman Stephen McCausland said.

“It just doesn’t happen,” he said before Monday’s press conference. “It’s a very rare case.”

The investigation is still “very open,” Massey said. “Nothing, obviously, is off the table.”

Police have fielded many tips from the public, though Massey couldn’t say how many. He said police were including all leads in their investigation.

Anyone with information about the case is asked to call Waterville police at 680-4700.

The Associated Press contributed to this report.