Convicted rapist Larry Murphy is a person of interest in the murder case of an 18-year-old Irish woman who vanished over 20 years ago.

Deirdre Jacob was last seen at the gateway of her home outside Newbridge, Co Kildaire on July 28, 1998 at about 3pm. The investigation into her disappearance was reclassified as a murder probe in August 2018 after gardai discovered new evidence about the case, The Irish Sun reports.

Chief Superintendent Brian Sutton told RTE's Prime Time: "Yes, Larry Murphy has been speculated about in the papers. Larry Murphy is one of a number of persons we are currently interested in."

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Murphy was released from prison in 2010 after he was convicted in 2001 of the kidnapping, raping, kidnapping, and attempted murder of a woman in the Wicklow mountains in February 2000.

The Irish Sun reported that an inmate at Dublin’s Arbour Hill prison made a statement to gardai in 2011 claiming that Murphy told him he had kidnapped a woman outside Newbridge by pretending to ask for directions.

A source said: “It’s well known in the prison that an inmate contacted gardai to claim Murphy told him one night he was behind Deirdre Jacob’s disappearance.

“The pair of them were drinking and taking drugs one night and the prisoner claims Murphy started rambling about his past and mentioned Deirdre Jacob.

CCTV footage shows Deirdre Jacob walking throughout Newbridge on the day she vanished.

CCTV footage shows Deirdre Jacob walking throughout Newbridge on the day she vanished.

“Murphy was hated in prison because of what he did to his victim and he had absolutely no friends. The prisoner didn’t think he would be considered a ‘rat’ because the inmates believed Murphy would always be a danger to women when he was released.

“The only reason Murphy would let his mask slip is if he was under the influence of alcohol or drugs as he doesn’t trust many people.

“The prisoner who came forward has been in jail for a long time, and if he helped to convict Murphy for murder he would be seen as a real hero.”

Police are hoping that enhanced and digitalized CCTV footage taken from around Newbridge on the day of Deirdre's disappearance will reveal clues that may have been previously missed.

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Deirdre’s parents, Michael and Bernadette Jacob, have renewed their appeal for information regarding their daughter’s disappearance.

Her mother said: "We miss everything about her and it's very hard."

Michael said: "We are appealing to you that has information or you're aware of someone who has information. Now is the time. Do the right thing and bring that information forward.

"You know that that information can help us and bring Deirdre home."

Deirdre Jacob has been missing since 1998.