Houston: The Indian-American foster father of 3-year-old Sherin Mathews, who has been sentenced to life in prison for the death of the toddler, has begun serving the jail term in Dallas.

In a case that attracted much international attention, Wesley Mathews, 39, pleaded guilty on June 24 to a lesser charge of injury to a child in Sherin's tragic death.

He was originally charged with capital murder by authorities in the US state of Texas after they discovered Sherin's highly decomposed body after a massive search that lasted 15 days.

On Thursday (July 24), Dallas County Sheriff officials said that Mathews was transferred from Dallas County jail to state prison at around 12:58 am that day.

A Dallas County jury heard the case, and Mathews was sentenced to life in prison in Sherin's death on June 26. Mathews has since filed another appeal in the case asking for a new sentencing trial. His attorney alleges photos of Sherin's body were "prejudicial".

"Jurors expressed visible emotion when shown the exhibits," defence attorney Brook Busbee wrote in the appeal.

The appeal also claims that evidence of prior injuries on Sherin's body "prejudiced the jury". The court filing said that those injuries cannot be linked to Mathews.

The father had reported Sherin missing after he put her outside October 7, 2017, because she wouldn't drink milk. Her badly decomposed body was found 15 days later in a culvert.

Prosecutors argued Mathews hid his crime, making it impossible to determine exactly what happened to the girl because of how badly decomposed her body was.

Mathews testified that his daughter choked on milk and that he had wrapped her body in a trash bag because he wanted "to do something nice" for her.

Sherin's adoptive mother, Sini Mathews, was also criminally charged after the child's body was found, but that case was later dismissed after the Dallas County District Attorney said there was not enough evidence to prosecute.

Mathews and his wife Sini, both hailing from Kerala, adopted Sherin from an orphanage in Bihar's Nalanda district in 2016.

Police charged Sherin's foster mother Sini with child abandonment in November 2017, after Mathews told officials that the couple left the toddler alone the night of her death while they went to dinner with their biological daughter.

Sini's case was dismissed in March this year after prosecutors said they could not prove it beyond a reasonable doubt.

Sherin's death attracted the attention of the Indian government and then external affairs minister Sushma Swaraj took keen interest in the case and also instructed the Indian mission in Houston to make sure that the Indian toddler received justice. India revoked the Overseas Citizenship of India (OCI) immigration status of Wesley and Sini after Sherin's death.

The government further tightened the adoption process after Sherin's tragic death.