From Dundalk's 'The Argus' in June 1996, showing Liam Adams (far right) beside Martin McGuinness at the opening of a Sinn Féin office

Suspected paedophile and senior Sinn Féin member Liam Adams chaired a commemoration for IRA martyrs over a year after his brother Gerry claims to have "moved immediately" to have him expelled from the party.

Liam Adams chaired the Edentubber Martyrs' commemoration in Co Louth attended by 1,000 republicans on 9 November 1997. He introduced the main speaker, Sinn Féin national chairman Mitchel McLaughlin. The event was reported in The Dundalk Democrat.

A Sunday Tribune investigation has uncovered a massive cover-up of Liam Adams' Sinn Féin involvement. He is portrayed as playing a short-lived, minor role. Louth TD Arthur Morgan claimed Liam Adams "was never a party officer".

Today, we reveal Liam Adams was Sinn Féin's most senior official in Co Louth. He was chairman of the Louth comhairle ceantair, liaising directly with the national Sinn Féin leadership.

In June 1996, he welcomed Martin McGuinness to Dundalk and stood beside McGuinness at the official opening of Sinn Féin's new office in the town. In Dundalk's The Argus, McGuinness is photographed cutting the ribbon with "Liam Adams, chairman of Louth comhairle ceantair" by his side. It's inconceivable Gerry Adams didn't know of his brother's senior position then.

Liam Adams is wanted by the PSNI on charges of repeatedly raping his daughter, Aine Tyrell, from the age of four. He denies the allegations but Gerry Adams has said that when Aine told him in 1987, he believed her.

As Louth comhairle ceantair chairman, Liam Adams was over all Sinn Féin cumainn in the county and was their go-between with the leadership. He couldn't have held this position without the national leadership's approval.

Gerry Adams admits knowing Liam was in Sinn Féin only when he heard he was seeking the Sinn Féin 1997 Dáil nomination in Louth. The Sunday Tribune can reveal Liam sought this in October 1996. Gerry Adams said he then "moved very, very quickly" to have him "dumped" from Sinn Féin.

Yet eight months later, Gerry Adams canvassed in Dundalk with Liam and a further five months after that Liam chaired the Edentubber 40th anniversary commemoration for five IRA men killed in the Border campaign.

After Bodenstown, it's the most significant individual commemoration in the republican calendar. A veteran republican said: "I'm appalled the leadership let this man take part in such an important republican event."

The Sunday Tribune can reveal that, apart from attending Liam's second wedding, Gerry Adams also attended the christening of one of Liam's children in Dundalk's Holy Cross Church in 1997 – 10 years after he believed Liam was a paedophile.

Meanwhile, Sinn Féin's 1997 Louth election agent, Fra Browne, has contradicted claims by Gerry Adams' spokesman that the Sinn Féin president hadn't wanted Liam on the Dundalk canvass but was in a difficult position when he turned up.

"The Adams brothers weren't estranged. They got on great together," Browne said. "Liam didn't gate-crash the canvass. Pretending he did is rewriting history."

Both Browne and Sinn Féin Dáil candidate Owenie Hanratty are angry that they unknowingly canvassed with a suspected paedophile. Both men have since left the party.