A Florida woman’s shredded jailhouse letters to her then-fiancé led police in January to arrest her in the 1986 murder of her 3-year-old son, who she claimed went missing in Nevada during a swap meet, authorities revealed.

Amy Elizabeth Fleming, 60, was extradited to Nevada following her arrest in Florida on Jan. 29, when officials found enough evidence to arrest her in the murder of her son, Francillon Pierre, more than three decades after she reported him missing.

North Las Vegas Police Chief Pamela Ojeda said in a Monday news conference that detectives reopened the missing boy’s cold case in 2017 while trying to trace the origin of a fraudulent birth certificate application in the name of the missing boy.

They believed someone was trying to commit identity theft, but then uncovered other interesting items in the missing person case, including a jail notes between Fleming and her then-fiance Lee Luster that was torn into dozens of pieces.

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Those letters told a different story than what the couple initially reported of Francillon’s disappearance.

"What happened was totally unintentional, I'm sorry, you know that," Fleming wrote to Luster while the two were jailed for several months in 1987 for obstructing the investigation, according to a police affidavit submitted to obtain a Dec. 13 warrant for Fleming's arrest.

In another letter, Fleming told Luster: "You're the only one I have left to care about. My family is not there, Yo is not there, I cannot face my friends for fear they will be implicated."

Two witnesses whose names were blacked out in the affidavit also told police they overheard Luster tell a woman in a jailhouse meeting area that "Amy had killed the baby."

Francillon, nicknamed Yo-Yo, was last seen on Aug. 2, 1986, at the Broad Acres Swap Meet in North Las Vegas, the Palm Beach Post reported. Fleming, whose was 28 and went by Amy Luster at the time, and Luster told police they lost track of the 3-year-old.

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The boy, whose body has not been located, was listed as missing.

The couple was suspected of foul play, but no formal charges were filed against them. Authorities found the Lusters were charged with felony child abuse in December 1985 for allegedly beating Francillon and were awaiting trial when the child vanished.

They received five years’ probation after pleading no contest to the charge.

“Even though Detectives were suspicious that Fleming was involved in the disappearance of Pierre, there was not enough evidence at the time to prove or disprove her involvement. Shortly after Fleming and Luster were released on the obstructing charge [in 1987], they moved to Florida,” police said.

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Fleming was arrested in January at her marketing job in Boca Raton, Fla.

Luster, now 62, has not been charged with a crime.

The Associated Press contributed to this report.