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A woman who built an online following blogging about her sickly young son could soon face charges after authorities determined that his death last January was caused by a lethal dose of sodium injected into his feeding tube, a source close to the investigation told FoxNews.com.

Five-year-old Garnett Spears, of Chestnut Ridge, N.Y, died at Westchester County Medical Center Jan. 23, after being hospitalized, first at Nyack Hospital, several days earlier. Although his mother, Lacey Spears, had for years blogged of his health problems, authorities became suspicious when doctors discovered the alarming sodium level in the child's body, and the Westchester County medical examiner has ruled the death a homicide, according to the source.

"It's evident by the nature of what was found in his body that somebody, in effect, poisoned him," the source, who was not authorized to speak publicly on the matter, told FoxNews.com. "He [Garnett] died at the hands of somebody else."

Prior to his death, the boy had become known as "Garnett the Great" to an online circle who followed reports by his mother, Lacey Spears. She chronicled his many hospital stays and dietary problems on a blog, "Garnett's Journey," subtitled "Healing takes courage, and we all have courage, even if we have to dig a little to find it."

But the source who discussed the case with FoxNews.com said that shortly after the boy was hospitalized for the last time in his short life, his mother called a neighbor and asked that she destroy any evidence of feeding tubes within the home.

"She wanted the neighbor to dispose of incriminating evidence," the source said. "The neighbor never did get rid of it and police seized it." That accusation was originally reported by The Journal News, which was the first news outlet to launch an in-depth investigation into the case.

Spears' attorney, David Sachs, denied any wrongdoing on the part of his client.

"Lacey is completely devastated by the loss of her son and absolutely denies harming her son in any way," Sachs said in an email to FoxNews.com.

The Journal News interviewed a friend of Spears, who reportedly told the paper that Spears expects to be charged with murder. A source with intimate knowledge of the case told FoxNews.com charges could range from murder to manslaughter to reckless manslaughter to criminal negligent homicide. The source declined to elaborate on when a decision will be made.

Spears has relocated to Kentucky, where she is staying with family, and could not be reached for comment. The 26-year-old single mother had moved from the South to live in the quiet "Fellowship Community" in Chestnut Ridge, N.Y. -- a close-knit, rural community about 30 miles north of New York City that cares for the elderly and prides itself on organic farming and other self-sufficient means of living. The legal responsibility for the community is carried by the Rudolf Steiner Fellowship Foundation, Inc., a non-profit licensed by New York state as an adult care facility, according to its website.

While few at the Fellowship were willing to speak about the ongoing investigation over the weekend, friends of Spears in her native Decatur, Ala., are reportedly shocked over the ruling.

"I've been on the phone all afternoon with mutual friends and they're all saying, 'I can't believe this,'" Shawna Lynch, a friend from Spears' former hometown, told the Journal News. "We're devastated, mad, angry, hurt, shocked. We all wanted to believe Lacey and be there for her. But with the evidence the way it is, everyone feels the same way I do. Justice needs to be served."

In an April 18 posting on her Facebook page, Spears put up a photo of her son holding a toy with the comment, "I want to carry on his legacy & the only way I can right now is to write about him & share his pictures." Earlier postings show a beaming blond boy riding a red bike, sitting on the beach with his mother and eating solid food.

Garnett Spears first received a feeding tube when he was a baby. Since that time, his mother has publicly detailed her life with her son on social media websites, like Facebook. She would often post comments about her son's many hospitalizations -- even posting pictures of her son in his final hours at Westchester County Medical Center, where he was airlifted from Nyack Hospital after being admitted there in mid-January for seizures.

Investigators are looking at the possibility the boy's mother suffers from Munchausen by proxy, a psychiatric disorder and rare form of child abuse in which a parent or caregiver harms a child to seek the attention and sympathy of others.

"These are people who are desperate for attention and seek it through creating a sensational scenario," said Dr. Manny Alvarez, senior managing health editor of FoxNews.com.

In the case of Munchausen by proxy, "the parent is seen as almost a hero," Alvarez said. "The reality is that they do these actions being aware that they're lying."

"It's extremely difficult to diagnose," noted Alvarez, who said only through "extensive" interview and observation can psychiatrists trained in the syndrome identify it.

It remains unknown whether Garnett ever needed a feeding tube in the first place, and medical personnel in at least two states declined to comment, citing patient privacy laws. Members at the small Fellowship community, meanwhile, reported seeing the boy eating solid foods on several occasions without a problem.

Click for more from FoxNews.com on Munchausen syndrome