BALTIMORE (AP) — A woman who authorities say confessed to suffocating her 1-year-old son in December has been arrested.

Shakira Shaw, 22, was charged with murder on Monday, about a month after she informed authorities she was responsible for Kaleb Shaw’s death last December, the Baltimore police department said in a news release.

Baltimore police said Kaleb was brought to a hospital last year and died there a short time later.

An autopsy conducted after Kaleb’s death had determined he died from natural causes. It is not clear why he was initially taken to a hospital by firefighters.

It was not clear if Shakira Shaw had an attorney who could comment.