After finding marks on her children, a mother suspected the worst about a male baby sitter listed on a website. Whenever she needed someone to take care of her sons, she avoided the name Yuji Motte.

But her two young boys ended up in the care of Motte, a suspected pedophile who pretended to be a woman on the site. The body of one son was discovered in Motte’s apartment in Fujimi, Saitama Prefecture, in March 2014. The younger son, deprived of food, suffered from health problems.

At his trial, the court heard that Motte had molested at least 20 children.

But even if Motte had wanted help to prevent his pedophilia from leading to crimes against children, he would have few places to turn to in Japan, according to experts.

“Japan’s treatment system is lagging about 30 years behind, compared with the United States and countries in Europe,” said Hiroki Fukui, a psychiatrist who heads the nonprofit organization Sex Offenders Medical Center (SOMEC).

Experts say Japan lacks specialists on pedophilia who can form a network to prevent such crimes. They also cite the limited number of medical institutions that can treat offenders.

In response to calls to keep children safe from pedophiles, the Justice Ministry began a rehabilitation program in fiscal 2006 for prisoners convicted of sex crimes and offenders on probation. But Japan is ill-equipped to deal with such sexual predators before they can harm children.

The Yokohama District Court in July sentenced Motte, 28, to 26 years in prison for killing the 2-year-old boy.

According to the ruling, Motte, with the help of an accomplice, abducted the two brothers for several days with the intention of sexually assaulting them. He molested the 2-year-old before smothering him.

The boy’s brother, who was 9 months old at the time, went for hours without being fed.

The court also acknowledged Motte had sexually abused 20 children, including those aged from 4 months old to 5 years old. He had taken pictures of some of the victims’ genitalia. Other children were tied with string around their abdomens.

“The crimes he committed are extremely heinous in that he routinely committed sexually offenses against children,” Presiding Judge Takao Katayama said in his ruling. “The fact that he denies having pedophilia raises concerns that he will repeat his sex crimes.”

Motte appealed the ruling in August.

A psychiatrist who examined Motte told the court that the suspect indeed had pedophilia, a condition in which the person has an intense sexual attraction to prepubescent children.

“It would be preferable if he continues to be treated throughout his life,” the psychiatrist said. “He needs to check his sexual orientation on a regular basis.”

The Justice Ministry’s rehabilitation program centers on cognitive-behavioral therapy and is aimed at making sexual predators realize the “distortions” in their desires and understand the consequences for the victims.

Program participants are also asked to draw up action plans on, for example, how to control their urges.

So far, more than 4,500 offenders have taken the program, according to the ministry.

Many nations in the 1980s tightened penalties against sex offenders as a deterrent. But it became clear that simply locking up the assailants had little effect on preventing recidivism after their release.

Japan’s penal system focuses on rehabilitation and helping convicts assimilate into society through affordable therapies and other assistance after they serve their sentences. But it is not really designed for pedophiles.

At SOMEC, about 300 perpetrators of sex crimes gather monthly for cognitive-behavioral therapy in Tokyo, Osaka and Fukuoka. They pay for their treatment, and some are prescribed medication to reduce their sexual desires.

Fukui of SOMEC said a sweeping overhaul is needed for Japan to catch up with other nations in treating sex offenders to prevent crimes against children.

“Japan is still at the stage where it is trying to determine what kind of a setup should be in place to rehabilitate sex offenders,” Fukui said. “Right now, recipients are hard-pressed to pay for their treatment. The existing public health insurance system should be overhauled to offer affordable care.”