A 14-year-old girl suspected of prostitution told police her mother and grandmother, both convicted prostitutes, forced her to sell her body to pay their living expenses, prosecutors said on Thursday.

Alicia Melchor, 33, and Elizabeth Buford, 55, were arrested Tuesday on charges of compelling prostitution after the girl led police to a motel room after they picked her up on Telephone Road, prosecutors said.

The second-degree felony carries a maximum punishment of 20 years in prison, if the two are convicted.

The pair remained in the Harris County Jail on Thursday. The teen was not in custody.

Buford also was charged with possession of a small amount of heroin.

The teen was observed by police attempting to prostitute herself, said Donna Hawkins, a spokeswoman for the Harris County District Attorney's office.

"She gave a statement to police that her mother and grandmother required her to prostitute herself to pay for their living expenses," Hawkins said.

The girl's mother and grandmother each have several convictions for prostitution during the past 20 years.

Although familial relations are not uncommon in sex trade accusations, three generations of prostitutes is unusual, said Charlie Vasquez, a Lieutenant in HPD's vice division.

"I've never heard of anything like that," he said. "Generally, prostitution takes place after someone has been alienated from their family."

Vasquez said officers working with HPD's juvenile sex crimes division, not the Houston Police Department's vice squad, made the arrests. Calls to those officers were not returned Thursday.

Other vice officers said online advertisements for "mother and daughter" prostitutes also are not unusual.

brian.rogers@chron.com