Police investigating missing Maine toddler Ayla Reynolds have officially turned their focus to the three adults who were in the family home on the night she disappeared, claiming the evidence does not point to an abduction.

State and local detectives now assert that the 20-month-old's father, Justin DiPietro, his girlfriend and his sister know more than they're telling police.

And after DiPietro's dubious polygraph test and the discovery of a significant amount of blood in the house, some on Ayla Reynolds' mother's side of the family are inclined to agree.

Ayla Reynolds Disappears

Ayla Reynolds had been placed in her father's care while her mother Trista completed a substance abuse program in Lewiston, Maine.

When she disappeared the night of Dec. 16, the blond, blue-eyed little girl was wearing green pajamas with Daddy's Princess written across the chest. One of her arms was in a soft cast after an accidental break a few weeks before her disappearance.

According to Justin DiPietro, Ayla went missing the night of Dec. 16. On the night she was last seen, DiPietro, his girlfriend Courtney Roberts and her own child were sleeping in the basement.

DiPietro's sister was with her child on the main level of the one-story house, and Ayla was in a bedroom on that floor by herself.

When DiPietro discovered Ayla had gone missing in the morning, he called the police, and gave every appearance of being a grieving and distraught father.

Blood Found in Maine Home

But on Jan. 28, six weeks after Ayla Reynolds went missing, police revealed that blood had been found in the Waterville, Maine home.

Though investigators would not confirm that the blood was that of the missing toddler, State Police spokesman Steve McCausland told the AP that the existence of the blood was troubling. He also said that it was found in the house's basement, which DiPietro used as his bedroom.

Officials told Trista Reynolds, meanwhile, that the blood they found was more than a small cut would produce, according to ABC News.

'To say he didn't know is just not true.'

Word that blood was found in the home where the three adults were staying comes just one week after another suspicious twist in the story: Justin DiPietro took a polygraph test shortly after Ayla went missing, then lied about the results.

DiPietro, in an interview with the Morning Sentinel, said that he asked to be given a polygraph the moment his daughter went missing, but that he didn't know how he had done.

I was never allowed to see them [the results], he asserted. It's something you're going to have to ask law enforcement about.

McCausland was baffled by DiPietro's statement.

He knows how he did, because we told him, the spokesman said, though he would not comment as to how whether the missing girl's father passed or failed.

To say that he didn't know is just not true, he told the Portland Press Herald.

Adults Don't Pass 'Straight-Face Test'

Everything is open, Police Chief Joseph Massey told CBS News a month ago, when he admitted that abduction was still a real possibility. Everything is on the table.

Now, however, DiPietro's odd response to his polygraph test, the blood found in the Maine home and the several gaps in the three adults' stories have investigators focusing in on DiPietro, his sister and his girlfriend.

The adults inside that home say that someone came into the house--a small home--went into a bedroom Ayla normally doesn't sleep in, took her, vanished in the night-- and not one of them heard or saw anything, McCausland told ABC News.

Later on, McCausland reiterated his views, saying none of the adults' stories passed the straight-face test.

We've followed every conceivable piece of evidence that would follow their version of events, he told the AP. And we have found not one piece of evidence that supports an abduction.

'They know more than they're telling us.'

Police have not named DiPietro a suspect, or even a person of interest in the investigation. Investigators say they are no closer to solving the case than they were on the morning of Dec. 17, 2011.

In December, Trista Renolds admitted that she had filed for sole custody her daughter the day before Ayla disappeared, but said DiPietro was not aware of the paperwork.

McCausland also said that detectives weren't singling out any of the three adults.

 We think they know more than they're telling us, The Washington Post quoted him as saying.

'He was supposed to protect her!'

But for Trista Reynolds and her family, the evidence against DiPietro, even if he didn't harm his daughter himself, has never looked more damning.

All I know is that he was the last one to see my daughter, Trista Reynolds told ABC News back in December. All I want to know is where she is.

Ayla's maternal grandfather, Ronald Reynolds, said he took the day off Monday because he couldn't take any more news reports about his missing granddaughter.

He told The Post that he looks at Ayla's photo every night before he goes to sleep.

I look at her and wonder why, why would anyone want to hurt that little girl? he said.

But his confusion quickly turned to anger against the Maine toddler's father. He was supposed to protect her, Reynolds said of DiPietro. He didn't even do that.

Reynolds Family Issues Appeal

In Waterville, Maine, local residents remain concerned and perplexed by the developments in the case.

The search for Ayla Reynolds has included massive searches by game wardens and FBI agents, with local streams drained and searched by divers as part of the investigation.

The Reynolds family, meanwhile, continues to run the Web site www.aylareynolds.com, and has issued an appeal following investigator's revelations urging anyone with information to come forward.

Even in light of this evidence we are more determined than ever to find out what happened to Ayla, the message read. We cling to the hope that she is alive and will be returned to us.

We urge anyone that has information about Ayla to come forward now, and unburden yourself of the truth.

Ronald Reynolds added a personal appeal as well, charging whoever took the missing Maine toddler to let the family know what happened.

Right now I feel so helpless, said the former Marine. Enough is enough. I'm tired of it.

Someone ought to have enough guts to stand up to the plate and say where she is so we can have closure, he added. If for some reason my little girl is not with us, then we need to bring her home.