A Maryland mother who, 'took a Lyft to a dumpster' to allegedly dump her four-year-old son's body, has confessed to police that he was put in a hot bath and had suffered burns so severe that his skin was floating in the water around him.

Authorities, including the FBI, had been searching for Malachi Lawson after he was reported missing from the porch of his grandmother's home in Baltimore on Thursday, August 1.

But the boy's mother Alicia Lawson admitted on Friday night that Malachi was actually dead. She and her wife, Shatika Lawson, 40, have both been charged in connection to the child's death.

Alicia, 25, led police to Malachi's remains on Saturday. His body was found in a metal trash bin and had 'obvious signs of injury'.

Baltimore police said the child suffered severe, untreated burns before he was found.

A Maryland mother who, 'took a Lyft to a dumpster' to allegedly get rid of four-year-old Malachi Lawson's body, confessed to police that he was put in a hot bath and had burns so severe that his skin was floating in the water around him.

Charging documents released Monday have revealed more details leading up to the boy's death.

The documents say Alicia and Shatika told police that Malachai was burned by bath water so hot that his skin was floating around him.

Police said they feared getting punished, so tried to treat the burns themselves.

They said Alicia found her son unresponsive nine days later in a 'puddle of wetness'.

She allegedly wrapped him in a blanket and caught a Lyft to a dumpster nearly 10 miles away.

Investigators said they tested the water at the couple's home but found that 'at no time' did the bath water exceed lukewarm temperatures.

Both women face charges including involuntary manslaughter, child abuse and false statements.

The pair could face further charges once a medical examination has been completed, police commissioner Michael Harrison warned.

Malachi had likely been dead since August 1, police said.

The FBI grew suspicious after finding that the mother reportedly had searched for trash collection sites on the web, prosecutors claim.

The boy's mother, Alicia Lawson (left), admitted on Friday night that Malachi was actually dead and not missing. She and her wife, Shatika Lawson (right), 40, have both been charged in connection to the child's death

Speaking on Saturday, commissioner Harrison said: 'Last night after extensive interviews with Malachi's mother, Alicia Lawson, she confessed that her son was not missing, but deceased.

'She subsequently gave detectives the location of the child's remains which were in the 5500 block of Haddon Avenue.

Baltimore police, Maryland state police and the FBI all assisted the ultimately futile search for Malachi when he was initially reported missing.

The child's body was transported to the medical examiner's office for an autopsy, Harrison said.

The investigation has been handed over to Baltimore Police's homicide division.

Shatika Lawson's lawyer said she had no malicious intent.