Schwerzenbach, Switzerland ? Twice a week, on average, in a nondescript building by the railroad tracks, a foreigner comes to die.

Most are terminally ill. Some are young and physically healthy except for a permanent disability or severe, debilitating mental disorder.

Drawn by Switzerland’s reputation as a trouble-free place for foreigners to end their lives, more than 100 Germans, Britons, French, Americans and others come to this small commuter town each year to lie down on a bed in an industrial park building and drink a lethal dose of barbiturates.

Now the country’s suicide practices are under the spotlight after British TV last week showed Craig Ewert, a 59-year-old Chicago man with a severe form of motor neuron disease, killing himself in Switzerland two years ago.

Other countries, including the Netherlands, Belgium, and Oregon and Washington in the U.S., have recently passed laws allowing the incurably sick to seek out a doctor who — under tightly regulated circumstances — can hasten their death.

But only Switzerland, in a law dating back to 1942, permits foreigners to come and kill themselves, placing few restrictions on the how, when and why. Doctors have relative freedom to prescribe a veterinary drug for that very purpose.

Five minutes after drinking a glass of water laced with sodium pentobarbital, they fall asleep.

Death follows about half an hour later.

Like Ewert, most foreigners turn to Dignitas, one of several Swiss organizations dedicated to the cause. Dignitas’ founder, Ludwig A. Minelli, has built the group into a thriving nonprofit operation.

Critics accuse it of turning Switzerland into a magnet for so-called “suicide tourism,” and of operating on the fringes of medical ethics and public opinion.

Dr. Bertrand Kiefer, editor-in-chief of the Revue Medicale Suisse, a medical journal, fears some people are killing themselves not to escape intolerable suffering but to relieve family or society of a burden.

Dignitas says its members’ right to self-determination is paramount. The only criteria for assisting a suicide are that the person “suffers from an illness that inevitably leads to death, or from an unacceptable disability, and wants to end their life and suffering voluntarily.”

Kiefer also says assisted-suicide groups lack financial transparency.

Dignitas says it charges $8,300 for its services, which include taking care of legal formalities and arranging consultations with a doctor willing to prescribe the deadly medicine. The group says it pays its staff salaries and invests any profit in its advocacy and counseling work, which includes suicide prevention efforts.

Other such organizations in Switzerland say they are cheaper and do not charge the patient directly, relying instead on membership fees and donations.

“We need to ensure that there’s no economic incentive for these organizations to encourage people to commit suicide,” Kiefer said.

A small religious party is campaigning to ban groups from charging for their services — an idea which the pugnacious Minelli calls the product of “sick brains.”

Officials in the canton of Zurich threatened to restrict their activities by making doctors see each patient more than once, and by limiting the supply of sodium pentobarbital. So some groups hoarded the drug, while Dignitas turned to plastic bags and helium.

The bag is placed over the head of a person who then opens a flow of helium, falls into a coma and dies “in 99.9 percent of cases,” according to Derek Humphry, a British author whose suicide manual “Final Exit” has sold at least a million copies.

But the use of helium smacked to many Swiss of Nazi gas chambers, and made Minelli a tabloid hate figure — a sentiment widely shared in Schwerzenbach.

Like most Swiss, the townspeople support the principle of assisted suicide, but “the helium was the last straw,” said Manfred Milz, who is evicting Dignitas from his building.

It has to leave by June — its third move in two years. Dignitas previously used a private home, hotel rooms, even mobile homes.

But demand continues to grow, Dignitas says, and its membership has reached nearly 6,000 over the past decade. Some are merely supporters of its work, others intend to die with its help when the time comes.