A father penned a tragic letter to authorities months before his daughter's death in a bid to warn them about the abuse he believed his daughter was suffering at the hands of her mother and her partner.

Mickhal Garrett, from Cleveland, US, sent a chilling letter to Cuyahoga County Juvenile Court in December about the alleged abuse of his four-year-old daughter by her mother, Sierra Day, 23 and her mother’s boyfriend, Deonte Lewis, 26, News 5 Cleveland reported.

Aniya Day-Garrett died on March 11 after suffering from a stroke after she was allegedly beaten severely.

View photos Mickhal Garrett penned a letter to authorities to warn them about the abuse of his daughter. Source: GoFundMe More

But her father said the warning signs were evident months before.

“I truly, truly, truly feel as though our daughter is being abused at home physically/mentally and that her life could possibly be in danger,” Garrett wrote in the letter.

He said he had become increasingly concerned over his daughter's welfare when he discovered Aniya's body covered in cuts and bruises in September 2017.

View photos Sierra Day (left) and Deonte Lewis (right) have been charged over Aniya's death. Source: Cuyahoga County Sheriffs Department More

When he asked Day what had happened to their daughter, she stopped Mr Garrett from seeing Aniya.

"After trying to communicate with Sierra about our daughter's wounds is when Ms. Day began to tell me false stories, reject all my phone calls, my visitation and all quality time with our daughter," Garrett wrote in the letter.

Aniya's daycare had also noticed markings on her body as early as 2015 and kept a log of all her injuries before contacting Child Family Services (CFS).

In December, Mr Garrett's letter to juvenile court officials pleaded for his daughter's safety.

View photos Mr Garrett claims the CFS More

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