Dutch police probing the mysterious case of a family who were locked away on an isolated farm for nine years have arrested the father of the group.

Gerrit Jan van Dorsten, 67, was detained Thursday on suspicion of deprivation of liberty, harming the health of others and money laundering after tens of thousands of euros in cash were discovered at the property.

It comes after police arrested 58-year-old Josef Brunner, a groundskeeper at the farm and the family's former neighbour, on the same suspicions earlier this week.

Officers said they are probing 'whether a certain religion or philosophy' played a role in the detention, as it was confirmed the father was a member of the Family Federation for World Peace and Unification - known as the Moonies - in the 1980s.

However, the church said he suffered from mental health issues and left the movement in 1987.

Derk van Dorsten, Gerrit's brother, is still a member of the church but denied having any contact with his sibling since 1984.

A church spokesman added that they have no records of Brunner being a member of the church, after neighbours suggested he met Gerrit through the movement.

Elsewhere barman Chris Westerbeek, who alerted police to the family after eldest son Jan Zon van Dorsten walked into his bar, told of his relief at speaking up, describing Jan as 'unearthly' and adding that he was 'barely able to speak'.

Jan revealed how his family had not left their home in nine years, kept against their will in a nearby farmhouse

The eldest of the five children, Jan Zon van Dorsten, visited Chris Westerbeek's bar in Ruinerwold, 60 miles northeast of Amsterdam

Chris Westerbeek called police after he found out about the Dutch family kept locked in a cellar for nine years

Mr Westerbeek said that after noticing Jan's disheveled appearance and strange manner he became worried and engaged the 25-year-old in conversation.

He told The Sun: 'There was something unearthly about him that worried me.

'We live in a village where everyone knows everyone else and he was a total stranger when he walked in and drank those beers that night.

'But then I decided to find out what was wrong and will never forget that night. He struggled to communicate but he looked so desperate I knew I had to help him. Now I thank God I did.'

Police now believe that the six people found living at the farm were held against their will, after being initially unsure whether they went there voluntarily.

Brunner is thought to have met the reclusive father-of-five Geert Zon van Dorsten through the Unification Church - whose members are called 'Moonies' - after he dropped out of the Army in the late 90s, his family claimed.

According to locals at a holiday park where the van Dorsten family were taken after they were liberated, they moved in a circle together every 30 minutes in a ritual believed to relate to the Moonie cult, RTV Drenthe reported.

The Unification Church was founded by South Korean pastor Sun Myung Moon, who declared himself the Messiah in the 1950s, it was brought to the Netherlands in 1965.

A large amount of money in cash was found in the Ruinerwold farmhouse where the van Dorstens lived. It is believed this money came from donations from the Moonies.

Police bring in equipment into the farmhouse in Ruinerwold, 60 miles north of Amsterdam, where carpenter Josef Brunner, nicknamed Josef the Austrian, has been arrested for allegedly imprisoning his friend and his five children

Josef Brunner's old family home, his brother Franz said Josef had become delusional and stopped speaking to his family

Jan Zon van Dorsten, 25, is the son who alerted Dutch police to the plight of his four brothers and sisters and their father, who were living in isolation at a remote house while apparently waiting 'for the end of times'

Jan raised the alarm after walking from the house to a local bar where he ordered five beers and told the bartender that he couldn't go home

His disheveled appearance and strange manner worried the bar owner, who engaged him in conversation

Mr Westerbeek said the man, whose beard was 'dirty' and hair unkempt, said that he had been inside for nine years and that he wanted to end the way his family were living.

'He said he'd never been to school and seemed very confused. He spoke in a childish way,' said Mr Westerbeek. He told him that his siblings were between the age of 16 and 25.

The man told Mr Westerbeek that he 'needed help and wanted to put an end to the situation he was in,' according to Dutch newspaper Dagblad van het Noorden.

Mr Westerbeek contacted the police who searched the farm and discovered the family.

A former neighbour has revealed how Josef Brunner lived next door to the 'off-grid' family for a brief period in Hasslet, the Netherlands

Today, a court extended Brunner's custody for another two weeks. He is charged with unlawful detention and harming others' health, and will remain in detention for at least two more weeks.

Geert Zon van Dorsten's cousin said he had broken off contact with his family decades ago.

It was about thirty years ago. There was a lot of disagreements between my parents and Geert,' van Dorsten's cousin said.

Franz Brunner earlier said his brother was married to a Japanese woman and had become disillusioned from his family after joining the sect.

Police vans outside the property bring in equipment for their investigation

A police officer carries equipment as they prepare to make an investigation of the mysterious home

'My brother was always only for his own advantage,' he said. 'He was with a sect and he believed he was better than the Jesus.'

'When my father handed over the farm to me, the problems started. When Josef learned that I was in charge of the farm, he immediately demanded that I pay him for his services.

'For ten years, I have had no contact with him. The last time I saw him I said to him, 'You do not have to come back. I do not want to have anything to do with people like you.''

To those who knew him for the 16 years he lived in the Netherlands he was a secretive, quiet loner who rarely made friends and found it difficult to engage socially.

His brother Franz said the kidnap suspect had abandoned his twin daughters when they were young children and ignored them when they tried to contact him as adults in 2017.

When Brunner's father died in 2015 he did not attend the funeral and when his mother passed away 18 months ago, he failed to return calls to his family in Austria.

The family were discovered after the eldest son, 25, walked to a nearby bar on Sunday, ordered five beers, and asked for help

Franz said Brunner was born on March 3, 1961 in Waldhausen, Austria and was one of five peasant children.

He completed a carpentry apprenticeship with distinction, but while enrolled in the army in Linz he joined a sect.

The brothers quarrelled over their parent's farm and fell out with Brunner moving out.

Josef camped for a while in a house nearby and eventually moved in with an old aunt who lived in a 300-year-old house with a lot of land in Pabneukirchen, Austria, and appointed him as her heir.

He lived there from 1998 to about 2008, his brother says. He is then believed to have moved to Hasselt, the Netherlands, where he lived next door to the family he is accused of holding captive.

A former neighbour told MailOnline Josef lived briefly next door to the van Dorsten family but had left by the time Geert's wife had died from colon cancer.

Police in Ruinerwold on Thursday as they continue their investigation into Brunner's isolated house.