A sister of murdered journalist Lyra McKee has vowed to "support" her killers if they hand themselves in to police.
Nichola Corner said failure was not an option as she urged justice for her family and praised those who have given evidence to police.
Ms McKee, 29, was shot in the head by dissident republican group the New IRA while observing clashes with police in the Creggan estate in Londonderry last month.
Ms Corner said she would come to any police station to meet whoever admitted to shooting the talented journalist dead and help them through the experience - saying she was speaking in Lyra's name.
Her comments come as hundreds gathered for a rally at the conclusion of a three-day peace walk in memory of Lyra.
Snow Patrol frontman Gary Lightbody also joined the procession on the last leg on Monday ahead of the demonstration at Derry's Guildhall Square.
Ms Corner held the 1998 Good Friday Agreement aloft as she urged politicians to do a deal to end the threat of bombs and bullets once and for all.
"Here, in front of all of these people present, in the name of my sister, I offer to support you in the difficult task of coming forward and accepting responsibility for your actions," she added.
"I know that is not going to be easy, and it is certainly not going to be easy for me.
"But I am prepared to go there, I am prepared to have that difficult conversation, I am prepared to be there as you hand yourself in.
"I promise you here and now that I will meet you at any police station, anywhere on this island, to support you in taking the brave step of handing yourself in and allowing my sister the justice she deserves."
Ms Corner said she hoped the gunman needed relief from guilt and said he had not intended to turn himself into a killer.
"Yet the events as they developed led to that becoming your reality. You are now a killer, now the person who killed Lyra McKee, my baby sister, and you cannot take that back."
She added doing the right thing was sometimes the most difficult.
"Together we can end this nightmare because failure is not an option."
During the funeral a priest asked Northern Ireland's politicians why it took the death of a 29-year-old woman to unite their parties.
The latest talks process designed to restore devolved political powersharing was launched soon after the murder.
The Police Service of Northern Ireland (PSNI) released videos which appeared to show the moment a gunman fired the shots aimed at officers which killed the journalist.
Lyra had planned to propose to her partner, Sara Canning, and get married in the Irish Republic, where same-sex marriage is legal.
Ms Corner said: "I hope that no other family has to experience what we and countless other families have had to experience in this country and beyond.
"This has to be the end of bombs and bullets forever, and this is something that we the people can only achieve if we work together peacefully, each and every one of us.
"Everyone needs to remember that no one loses anything through equality, no one loses anything by seeking to work together and no one loses anything from peace."
Lightbody wore a T-shirt with a message of support for the family and used an acoustic guitar as he sang two tracks, one penned about his grandmother who lived in Londonderry and another - Light Up.
He said he was honoured to take part.
"If anybody feels frustration at our political system or frustration at our inertia in Stormont then perhaps we can look to the positivity today of people gathering together.
"That all they care about is that the people can be who they want to be, love who they want to love and live in peace and prosperity for all of our kids, for our nieces and nephews into the future."
A choir of ordinary people took part.
Some had never sung before and met only hours earlier but performed in front of hundreds.
They filled a temporary stage, crammed shoulder to shoulder and dressed in everyday clothes, as they sang the murdered journalist's favourite song, Smalltown Girl.
They also covered themes like people power.
Many in the crowd wore T-shirts in her memory and carried flags with messages of peace.
A spokeswoman for the walkers, Susan Curran, said: "We want to thank the McKee family for their honesty, their integrity, their love and their strength.
"Our hearts are broken for you but our hearts are open for you.
"As Lyra said, it won't always be like this - it will get better."