The man dipped a machete in a concoction of water, palm oil and kola nuts, held it in fire for several minutes, and then placed it on the right legs of the four suspects. None of the youths - ages 16 to 26 - appeared to flinch. They were deemed not guilty.
This practice known as 'sassywood' is banned under national law, but is still regarded as a legitimate form of justice by many Liberians. A suspect is subjected to intense pain and judged on his or her reaction - if the hot metal burns the person's leg, he or she is found guilty.
The UN has repeatedly warned that the practice is undermining efforts to improve human rights in Liberia as the country attempts to recover from 14 years of war.
Many legal specialists and human rights activists say relying on customs such as trial by ordeal - often harmful and even deadly - is down to the decrepit state of Liberia's judicial system. And many say not enough is being done to restore the sector, left in tatters by the war.
Four years after the fighting ended, progress in rebuilding the judicial and corrections system is "very slow", according to an August report by the UN Security Council. "The judicial system is constrained by limited infrastructure, shortage of qualified personnel, lack of capacity to process cases, poor management and lack of the necessary will to institute reforms." The report said most people do not have access to legal counsel.
Legal advisers in Liberia say the absence of functioning courts in most rural areas is due in large part to lawyers' reluctance to take judgeships there, as well as the lack of infrastructure for courts.
In the central Liberian town of Gbarnga in Bong County, 150km north of the capital Monrovia, residents told IRIN that trial by ordeal is the only means to adjudicate alleged crimes.
"If somebody is accused of stealing money, clothes, jewellery, food or other items, the best [way] to know who committed the act is to administer sassywood, which is fast - it takes less than 30 minutes to know who did the act," Gbarnga resident Johnny Bono said.
Users of sassywood believe the person administering it and the instruments used have mystical powers. Practitioners are paid in money or goods - up to 2000 Liberian dollars (US$32) per 'trial' in the capital and about a third of that in rural areas. Sometimes payment is kola nuts and a pure-white chicken.
According to a rights activist in Nimba County, the problem is that many people will submit to sassywood because they do not know it has been outlawed.
"Sassywood is very common here and most people believe that it is the only means of knowing a guilty person," said Dualo Lor of the church-based NGO Equip-Liberia in Nimba, 300km from Monrovia. "They are not even aware the practice is outlawed."
He group recently prevented the application of sassywood on a 32-year-old man accused of theft. "We have been trying very hard [to educate] the people about the danger of sassywood, but they just have not stopped it."
Some legal experts say it will be tough to stop if citizens do not feel they have a reliable justice system to take its place.
"The trial by ordeal in most parts of the country clearly shows that most people do not have confidence in the court system," Anthony Valcke, Liberia country director of the American Bar Association in Africa, told IRIN. "If people had such confidence, they would not resort to trial by ordeal."
"No amount of laws or government order can stop sassywood," Yerkula Zaizay, a resident of Gbarnga, told IRIN. "It is a tradition that our forefathers left with us. This is better than going to court. My late grandfather taught me how to apply sassywood and it is part of my culture so it cannot be easily stopped."
Gbarnga resident Bono said, "We cannot waste our time going to court. The sassywood is our courtroom. This is what our forefathers have been practising in the past and it has been working."
Lawyer Augustine Toe, head of the Justice and Peace Commission, a Catholic human rights group, said: "Sassywood undermines the justice system of this country and the rights of an accused are not protected. Our constitution provides that anyone is presumed innocent until proven guilty by a [court of law]."
Liberia's chief prosecutor, Tiawon Gongloe, told IRIN he had instructed all county prosecuting officers to arrest anyone carrying out trial by ordeal.
"We are aware sassywood is going on and this act is not only unlawful, but unconstitutional," he said, noting that 12 people were arrested earlier this year in southeastern Liberia for having administered sassywood.
UN independent human rights expert, Charlotte Abaka, said the government had to do more. "The Liberian government should take concrete steps to enforce the ban on trial by ordeal," she said, calling the practice a "grave" breach of human rights.