A man kidnapped two girls from their homes while their parents slept, took them to a construction site and raped them before sending them home, threatening to kill their families if they said anything, authorities said.

Erick Thomas Knapp Jr. (search), 31, confessed to investigators that he kidnapped, bound and raped the girls, ages 13 and 7, in separate incidents, sheriff's Capt. Michael Savage told the Charlotte Sun Herald for Sunday's editions. He said there may be more victims.

"He went into occupied residences and snatched children while their parents were sleeping in the next room," Savage said. "I don't know how much more of a monster" one can be.

Knapp was charged with kidnapping, armed burglary and sexual battery and was being held in the Charlotte County Jail (search) without bond. If convicted, he could face the death penalty for allegedly raping a person younger than age 12.

A woman who answered the phone at the jail early Sunday said Knapp would not be allowed to answer a reporter's questions and said she did not know whether Knapp had legal representation.

According to an arrest report, Knapp kidnapped the 13-year-old girl early Thursday from her South Florida home, tied her hands and blindfolded her. He took her to a house under construction nearby and raped her, then sent her home, saying he would kill her family if she told authorities.

The girl went home and told her parents, who called police. During the investigation, the 7-year-old came forward to say she had a similar experience weeks earlier, officials said. The girl had been afraid that Knapp would harm her family if she reported the crime.

Charlotte County Sheriff John Davenport praised the 13-year-old girl's courage for reporting the rape, which the sheriff said may have saved other young girls.

"This girl was very brave in coming forward," he said. "He would still be out there looking to victimize."

Port Charlotte is about 95 miles south of Tampa on Florida's Gulf Coast.

On April 16, the body of 13-year-old Sarah Lunde (search) was found near her family's mobile home in Ruskin, a Tampa suburb. Convicted sex offender David Lee Onstott has pleaded not guilty to first-degree murder and attempted sexual battery in her strangling death.