A registered sex offender in his 60s was arrested yesterday for the 1977 kidnapping of 6-year-old Mary Boyle in Co. Donegal. He is currently detained and facing questioning in Mullingar, Co. Westmeath.

“The last 37 years have been hell on earth,” the girl’s mother Ann Boyle told the Irish Independent. “That’s how I’d sum up what all the family have gone through.”

Despite the ongoing search since the kidnapping, this has been the first arrest made in relation to the case.

Assistant Commissioner for the Northern Region, officer Kieran Kenny, said in a public announcement that the man has been detained for up to 24 hours of questioning in Mullingar Station under the Criminal Justice Act 1984.

“A review into the circumstances surrounding the disappearance of Mary Boyle in Donegal in 1977 has been ongoing in the northern region for the last number of years. A dedicated team of personnel has been working on this investigation…which also involved extensive searches with the benefit of forensic and geology experts,” he said. “New lines of evidence have emerged, which have led us to where we are today.”

Though still very much heartbroken, Mary Boyle’s mother is relieved that an arrest has been made.

"I'm absolutely delighted that someone has been arrested, and my greatest wish now is that Mary is found," Mrs. Boyle said, following the arrest. "I want to find out before I die what happened my little girl. That means absolutely everything to me."

The six-year old went missing from near her grandparents’ home in Ballyshannon, Co. Donegal on March 18, 1977.

The suspect, who was arrested around noon yesterday in the Midlands, has several convictions for sexual abuse dating back to the 1960s, and is believed to be serving a current sentence for indecent assault.

"This person has been arrested in connection with the case, but whether he admits to it is another thing entirely,” Mrs. Boyle said. A Family Liaison Office has been continually updating the Boyle family on the developments in the case over the last 37 years.

Officer Kenny said that the arrest is directly related to new evidence arising from a review carried out in 2011, and that this breakthrough has brought them a step closer to uncovering Mary’s location. They are also using materials gathered from an investigation that took place in the early 2000s.

"We are appealing for anyone with any information on the circumstances around Mary's disappearance to contact us,” he concluded. “Even something that people may have thought was insignificant at the time could help us advance the continuing investigation."

A sex offender in his 60s has been detained in Co. Westmeath for the 1977 kidnapping.