More than 140 people have contacted police investigating the murder of Lyra McKee via the Major Incident Public Portal (MIPP).
Det Supt Jason Murphy said the public response had been "massive".
Ms McKee was shot as she observed rioting in Londonderry on Thursday.
It is understood that the PSNI and the Public Prosecution Service (PPS) have discussed what measures could be available to protect witnesses fearful of giving evidence at trial.
Det Supt Murphy said there had been a "palpable change" in community sentiment in support of their investigation since the murder of the 29-year-old on Thursday in terms of off-the-record intelligence.
He urged members of the public to "come forward and have a conversation with me".
"I want to reassure people that you don't have to commit to anything today. I just need to speak to people to understand what they know," he said.
"We can then look at how we capture that information in the best way possible to protect those witnesses and enable me to bring the gunman who killed Lyra McKee to justice."
The PSNI has asked to meet with local community leaders and influencers to help them identify any witnesses or those with information.
"This was an attack on the community. Lyra, tragically, was a random victim and I need the public to continue to support us," added Det Supt Murphy.
"My challenge is, how do I convert that community intelligence and information into raw evidence that allows me bring offenders to justice."
Ms McKee's funeral will held at St Anne's Cathedral in Belfast on Wednesday.
Her partner Sara Canning said the service would be a "celebration of her life".
It is understood the funeral service will be attended by political and faith leaders from across Northern Ireland.
Writing on Facebook, Ms Canning called on attendees to wear Harry Potter and Marvel related items.
Meanwhile, the Catholic bishop of Derry said the community in the nationalist area where Lyra McKee was shot dead needs to be "liberated" from dissident republicans.
The words "not in our name - RIP Lyra" have been added to the famous Free Derry mural in the city's Bogside area.
'Disgusted by what happened'
Ms McKee was standing near a police 4x4 vehicle when she was shot after a masked gunman fired towards police and onlookers.
A statement issued by the hard-left republican political party Saoradh on Friday sought to justify the use of violence on Thursday night.
Saoradh, which translates as liberation in Irish, has the support of the dissident republican group the New IRA.
A protest by friends of Ms McKee took place on Monday outside an office in Derry used by dissident republican political groups.
A number of women smeared red paint in hand prints on republican slogans outside the office.
Police were present. They filmed, but did not make any immediate arrests.
Bishop Donal McKeown said the "small" group of dissident republicans in Derry is a "danger to all of us".
He told the BBC's Sunday Sequence programme that people in the Creggan estate were "disgusted at what happened".
"The one liberation they require in that community is liberation from Saoradh," he said.
"We don't want to be laboured with a reputation that comes from a small group that represents a small number of people but is actually a danger to all of us."
Ms McKee's killing came 21 years after the Good Friday peace agreement was signed in Northern Ireland.
The 1998 peace deal marked the end in the region of decades of violent conflict - known as the Troubles - involving republicans and loyalists during which about 3,600 people are estimated to have died.
The Good Friday Agreement was the result of intense negotiations involving the UK and Irish governments and Northern Ireland's political parties.