A man whose brother was shot dead by British soldiers on Bloody Sunday has urged others to adopt Martin McGuinness's peace process mantle.
Politicians have until Monday to resurrect Stormont power-sharing after the former deputy first minister resigned in a dispute with his Democratic Unionist partners in government.
John Kelly was 23 when 17-year-old Michael died along with 12 other civilians after parachute regiment troops opened fire on a civil rights march in Londonderry.
He said: "The peace process is there and it is up to other people to take up the mantle that Martin left behind.
"Someone has to step into his shoes - they are big shoes."
He works at the Museum of Free Derry, which explains the story of Mr McGuinness's native Bogside to thousands of visitors from around the world.
The area was scarred by the 30-year conflict, Bloody Sunday in January 1972, Operation Motorman by the Army to retake control of the "Free Derry" autonomous area, frequent street riots, sectarian strife and wholesale deprivation.
Due to the Sinn Fein leader, Bloody Sunday was part and parcel of the peace process negotiations, Mr Kelly said.
A public inquiry in 2010 found the victims innocent.
Mr McGuinness told the probe that he was IRA second-in-command in Derry on that day.
The inquiry found that the future Sinn Fein leader was probably armed with a Thompson sub-machine gun.
He went on to become allegedly a senior IRA commander with blood on his hands and chief Sinn Fein peace process negotiator.
Mr Kelly said: "I would maintain that without Martin McGuinness we would not be where we are today.
"I believe that he was one of the most important figures during the peace process, not only during the signing of the (1998) Good Friday Agreement.
"I believe he was instrumental in keeping the peace process together over the years, throughout all the difficulties over the years.
"I believe that Martin was a steadying force throughout the whole process."
They first met at a rally in Manchester in 1973.
He recalled: "From that moment in time we became friends.
"Many's a time we chatted over the years.
"He was always there for the families, always attended the commemorations, the Mass, the march.
"He always supported the families."
He said his old companion was instrumental in obtaining funding for the Museum of Free Derry, established by the Bloody Sunday Trust and costing £2.4 million.
It tells the history of the area from the 1600s to the civil rights movement in the 1960s, including the Battle of the Bogside in 1969, a pitched riot which helped ignite the Troubles, Operation Motorman and Lord Saville's Bloody Sunday report in 2010.
Mr Kelly added: "Martin certainly helped to put it in place and the great pity is that he never saw it finished.
"We were hoping that he would come through his illness and were looking forward to the day he would walk through the door.
"But that is never going to happen now."