A reward of up to £10,000 has been offered for information about the murder of journalist Lyra McKee.
The Crimestoppers charity said the cash was available to anyone providing information which directly led to the arrest and conviction of those responsible for the dissident republican shooting in Derry last week.
Taoiseach Leo Varadkar stood alongside UK Prime Minister Theresa May at the 29-year-old's funeral in Belfast on Wednesday.
Sinn Fein leader Mary Lou McDonald was seated close to DUP chief Arlene Foster inside St Anne's Cathedral.
She said: "I think the first thing that needs to happen now to mark a step change in the political discourse is that the Irish and British governments need to meet in the British/Irish intergovernmental conference.
"They need to set out and articulate the outstanding equality issues and they need to map out a way forward.
"People now want resolution."
Fr Martin Magill, the priest leading the service, received a standing ovation when he asked why it took the death of a 29-year-old woman to unite their parties.
Mourners said they hoped pleas for action would not fall on deaf ears.
Mrs May said afterwards: "We must do our utmost to ensure that that does not happen."
The 100-year-old cathedral in the heart of Belfast was packed for the funeral, where there were tears and laughter for Ms McKee.
The congregation was led by Ms McKee's partner, aged 35, her mother Joan McKee, 68, brothers Gary and David and sisters Joan, Nichola and Mary.
Her family earlier paid tribute to a "gentle, innocent soul" whose "desire to bring people together made her totally apolitical".
Lyra's friends filled the pews wearing homemade #TeamLyra t-shirts, with Harry Potter-esque crests on the front.
Ms McKee was killed by indiscriminate fire as she observed clashes between police and New IRA dissidents on the Creggan estate in Londonderry on April 18.
The New IRA is an amalgam of armed groups opposed to the peace process and it recently claimed responsibility for parcel bombs sent to London and Glasgow in March.
Police believe the violence in Derry was orchestrated in response to an earlier search by officers aimed at averting imminent trouble associated with the anniversary of the Easter Rising.
Launching the reward for information, a spokesman for Crimestoppers, said it could "make all the difference in helping Lyra's loved ones and the wider community have the answers they deserve".
"This murder has sent shockwaves through the local community and across Northern Ireland. Indeed it has attracted global condemnation," they said.
"Ms McKee was merely doing her job as a freelance journalist.
"We know that this has affected all parts of the community and we urge anyone who has information about those who are responsible to come forward."
The independent organisation takes calls confidentially via a telephone or using an anonymous online form.
The spokesman said: "By contacting Crimestoppers, you stay 100% anonymous. Always.
"You can pass on what you know, safe in the knowledge that you're doing the right thing. No-one will ever know you contacted us and you may also be entitled to a reward."
The number to call is 0800 555 111 or the anonymous online form is available at Crimestoppers-uk.org.
The reward will expire on July 24.