Derick Boyce-Slezak (R) and his wife Mikala (L) have been charged with felony abuse or neglect of their baby boy. Police handout

A Missouri couple are alleged to have put their four-month-old baby in a microwave and caused him to suffer a fractured skull.

Derick Boyce-Slezak and wife Mikala, both 22, have been charged with felony abuse or neglect of a child after their child was taken into hospital with multiple injuries.

The couple, from Park Hills, took their child to the Cardinal-Glennon Hospital Emergency Room in April for a rash on his face, and the so-called "rash" was determined to be a second-degree burn.

Further tests revealed that the boy suffered a fractured skull and a subdural hematoma, a head injury that can cause swelling on the brain, according to court papers obtained by the St. Louis Post-Dispatch

Mikala claimed the burn was actually caused by a cleaning agent, telling officers that someone had cleaned the infant's face with a towel that contained a bleach-type disinfectant.

However, during a hearing earlier this week Mikala invoked her Fifth Amendment rights against self-incrimination, while Derick did not testify when they were quizzed about how the baby was injured.

But an employee from the Children's Division of the Missouri Department of Social Services said during the hearing that Mikala told her that the head wounds were from Derick dropping him, whilst he was trying to imitate what happened in a TV advert.

The Daily Journal reported that additional testimony from the employee stated that the baby had another fracture that was later found.

Court documents, filed in Missouri, showed that police investigators believe the boy was assaulted and put in a microwave for a "short period of time".

Reports say that the couple had a baby girl in January 2016, but waived custody of her shortly after she was born.

The pair were charged on Tuesday (28 November) in St. Francois County with felony abuse or neglect of a child and are being held in custody on a $500,000 (£370,000) bail each.