By Anita Oh

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AVONDALE, Pa. (CBS) — A man is in custody after allegedly kidnapping and sexually assaulting a 4-year-old girl in Avondale on June 10.

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The Chester County District Attorney’s Office and Pennsylvania State Police announced the arrest of 35-year-old Humberto Guzman-Garcia on Thursday.

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“The little girl, when we later talked to her, told us a monster came and took her out of the house,” said Chester County District Attorney Thomas Hogan.

Around 3:30 a.m. Sunday at the apartment complex on 1st Avenue, the girl’s parents woke up to use the restroom, noticed their front door was unlocked, and their little girl was missing.

“They’re frantically looking for her. Her mother’s looking inside, [stepdad] looking outside,” said Hogan.

Humberto Guzman-Garcia

Credit: Chester County DA

Hogan says the stepfather ran outside and spotted the man holding down his daughter by a shed about 50 yards away with his pants down.

“The father, of course, runs over right away. The defendant runs away,” Hogan said.

Authorities later found the suspect hiding in an abandoned car in the parking lot.

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Investigators say the man admitted to abducting the girl and committing a sexual act on her.

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He had initially knocked on the family’s door. The little girl, whose bedroom is adjacent to the front door, opened it.

The door was still locked by the top latch.

“Because she was so small, she could only unlock the bottom lock. She opened the door, the actor had a brief conversation with her through the crack in the door, at which point he reached in, opened the latch and took the child from the residence,” said Pennsylvania State Police Trooper Stefano Gallina.

The 35-year-old Mexican national is a legal resident of the United States, authorities say.

He faces multiple charges, including aggravated indecent assault and false imprisonment.

“This is every parent’s nightmare,” Hogan said. “It’s extremely rare for a stranger to be attacking someone like this. It’s a bold and brazen attack.”

Investigators say they have no evidence of stalking and believe this was a random, isolated act.

“My heart goes out to her,” said the victim’s neighbor, Dawn Clark. “He’s a monster and God forgive me for saying this but he’s lucky I didn’t find him.”

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Clark says the man knocked on her door that morning, too.

“He knocked on my door at 1 a.m., and I feel really bad because maybe if I would’ve called the cops, something wouldn’t have happened to that little girl. My heart goes out to her,” she said through tears.

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Guzman-Garcia is now in Chester County prison on $500,000 cash bail.