Neighbors told reporters she came out of the apartment acting frantically and swinging her arms

An Oregon mom has been charged with murdering her 12-year-old son authorities found the boy dead inside his Keizer apartment Saturday, PEOPLE confirms.

Amy Robertson, 38, has been charged with aggravated murder in the death of son Caden Berry, according to a Keizer police statement.

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Neighbor Brenda King told local station KGW that Robertson came out of her apartment Saturday acting frantically.

“I realized I didn’t see [Caden], so I said, ‘Where’s your son?’ She said, ‘In the house under the blanket,’ ” King told the network.

She said she went inside the apartment and saw Caden unresponsive. “I can’t even sleep because he was so young and so little,” King said.

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According to KOIN, Robertson was allegedly swinging her arms wildly and said something about demons when she exited her apartment.

Caden was a seventh grade student at Claggett Creek Middle School, according to the police statement.

On Sunday night, the community held a candlelight vigil in his honor. Friends described him to KGW as a happy person with a good sense of humor who enjoyed playing basketball and Pokémon.

One of his friends, Kaitlin Yusko, told the network, “He put a smile on your face, and I can’t believe this is happening. It’s just terrible,” adding, “I hope he’s flying high with the angels and I hope he’s really happy.”

Robertson cooperated with investigators upon being taken into custody, according to police.

She is being held without bail at Marion County Correctional Facility and will appear in court Tuesday at 3 p.m.

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An autopsy to determine the cause of death was scheduled for Monday, but Keizer police did not immediately return PEOPLE’s calls seeking additional details.