One girl was 5 when the alleged abuse began. The sisters are now 7 to 15, police said.
Karl Joseph Kraus was arrested Tuesday at his home near the northern city of Chiang Mai, where police confiscated about 100 photographs of naked children, said Doi Saket police Chief Kritapol Yeesakorn.
Some photos showed Kraus posing naked with other children, and police are trying to identify them and contact their families, Kritapol said. He said police were investigating if Kraus was part of a pedophilia network, noting many of the pictures were e-mailed overseas.
Kraus, who has lived in Thailand for more than a decade, approached the girls’ family in 2008 with an offer to teach the sisters English, Kritapol said.
“He would lure them into his house with sweets, usually chocolate from abroad or luxury sweets, and he would ask them to perform sexual acts with him,” Kritapol said.
“For the eldest of the four sisters, he recently gave her 4,000 baht ($120) instead of sweets.” The parents recently noticed the girls had lost interest in playing outside and asked them what was wrong, and then took them to police who immediately sought an arrest warrant, the police chief said.
Kraus was charged with rape and sexual abuse.
His Australian passport says he was born in Berlin. The Australian Embassy in Bangkok could not immediately be reached for comment on Wednesday. Kritapol said Kraus does not have a lawyer yet and has refused to talk to police until he has one.
Neighbors described Kraus as an active 90-year-old who still drives his own car, police said. But when police arrested him he appeared weak, walked with a cane and complained of diabetes and high blood pressure, Kritapol said. Police took him to a Chiang Mai hospital where he remains under surveillance.
The date of his next court appearance is not yet known.
Several Southeast Asian countries _ including Thailand, Cambodia and Vietnam - are magnets for pedophiles because of lax law enforcement, corruption in the justice system and poverty that forces children into prostitution.
