The broadcaster is to produce a series of four programmes about the brutal murder of Sophie Toscan du Plantier near her home in West Cork in 1996.
A separate documentary will focus on Karen Buckley, the nursing student from Mourneabbey in Co Cork, who was murdered last April after leaving a nightclub in Glasgow.
Ms Toscan du Plantier’s family allowed producers unprecedented access. The programme makers also secured access to Ian Bailey, who opened up his world to them in a way he has never done before.
The programme about Ms Buckley will retrace the events that led to her death and the police investigation that followed.
The producers said that while her death was a tragedy for her family and friends, it also raised important questions about safety and security that affect us all.
Investigative journalist Donal MacIntyre said he and renowned filmmaker Jim Sheridan would be also working with major British and French broadcasters in producing the documentary about Ms Toscan du Plantier.
Mr MacIntyre said producing a documentary about such an extraordinary case with many twists and turns was a highlight of his career.
This year Ireland got its second commercial broadcaster — UTV Ireland — but TV3 came out of its corner yesterday fighting fit.
It said it wanted to strengthen its position as Ireland’s most successful broadcaster.
In a three-part documentary, Vincent Browne is to take on Gerry Adams, described by the broadcaster as “the most controversial political personality on the island”. In the series, Mr Browne will explore the role that the Louth TD played in the Northern Ireland conflict and the peace process.
The show will also explore the politics of Mr Adams and of Sinn Féin from the perspective of whether they would make “any appreciable difference” to the welfare of the “ordinary people of Ireland”.
Mr Browne will also return to his Monday to Thursday Tonight show, but this time round, members of the public will be included in the debate with invited guests. However, anyone wanting to appear on the show will have to show proof of identification and promise not to be disruptive.
TV3 has committed to visiting 40 constituencies to give local people an opportunity to hold their local TDs to account. Mr Browne has been presenting The People’s Debate, which has already covered 20 constituencies and is well up for covering the remainder. He also indicated he had no plans to retire any time soon.
“We have plans for the 2016 general election and also the 2021 general election and the 2026 general election,” he said.