Samantha Rodriguez accused of killing son Liam who had autism

Liam Husted, 7, was discovered on a walking trail four days later. Photo / Facebook

WARNING: Distressing.

A mum in the US is facing a murder charge for allegedly strangling her autistic son after becoming "frustrated" with him.

A Coroner last week ruled that Liam Husted, 7, had died by homicide caused by strangulation.

On May 28, a child's body was found on a walking trail near Las Vegas, sparking a national search to identify him.

Liam's father, who has not been named, reported his son missing on June 1 after not hearing back from Liam's mother Samantha Moreno Rodriguez after she had taken their son on May 24.

A family friend contacted authorities to say that the description of the child whose body had been found near Las Vegas matched Liam, People reported.

Rodriguez was then arrested on June 8 and has since been charged over her son's death, the Las Vegas Review Journal reports.

Liam, who was on the autism spectrum, was last seen alive on May 24 leaving his California home in a car driven by Rodriguez.

Liam's father had reportedly returned home on May 24 to discover both Rodriguez and Liam missing from their family home.

Samantha Moreno Rodriguez has been charged with murder over her son's death. Photo / Supplied

Rodriguez, 35, is accused of strangling Liam for 15 minutes before he died, after becoming upset with him, prosecutors have claimed.

She allegedly confessed to the crime when questioned by police.

"This is an egregious case of filicide," Deputy District Attorney John Giordani said during a hearing last month.

"She essentially said that she became frustrated with the child and strangled him," he told the court.

Rodriguez is scheduled to next appear in court on August 3.