Police said evidence of planning for the shooting was found at Ramos's apartment in the city of Laurel, about 25 miles from the newspaper office.
He added: "Everyday we speak with someone who doesn't want to press charges".
Melissa Wilson, who came to the vigil with her husband, Benjamin, their 9-year-old daughter and 5-year-old son, said many Annapolis residents have "one degree of separation" from at least one victim. The request was denied.
A 38-year-old named Jarrod Ramos, who had a long-running dispute with the paper, has been charged with five counts of murder, according to court documents posted online by U.S. media. Four journalists and an advertising saleswoman were killed. The newspaper said two other employees had non-life threatening injuries and were later released from a hospital.
PC Altomare said the suspect had been "uncooperative".
"The moment I heard there was a shooting at the Capital, I told my wife, 'That's Jarrod Ramos, '" McCarthy said.
Ramos brought a defamation lawsuit in 2012 against Eric Hartley, a former staff writer and columnist with Capital Gazette, and Thomas Marquardt, then its editor and publisher, a court filing showed. In 2011, she took him to court, where he pleaded guilty to criminal harassment and was placed on 18-months' probation.
It had been dormant since January 2016.
When he was apprehended at the scene of the horrific crime in Annapolis, Ramos had no identification and seemingly would not speak to police.
In one haunting tweet in February 2015, Ramos' account said, "I'll enjoy seeing @capgaznews cease publication, but it would be nicer to see Hartley and Marquardt cease breathing".More news: USA representative from Wisconsin proposes dismantling of ICE
"As publisher of the Capital Gazette for nearly 40 years, this tragedy hits very close to home", Nancy Merrill, president of the family foundation, said in a statement.
Hutzell was quoted in Friday's edition saying "we are heartbroken, devastated". Pat Furgurson, a reporter, told the Guardian that the victims were "just trying to do their job for the public".
Altomare disclosed Friday that a detective investigated those concerns, holding a conference call with an attorney for the publishing company, a former correspondent and the paper's publisher.
The mayor of Annapolis, Gavin Buckley, addressed public views of the press after the attack on Thursday.
John McNamara, 56, pursued his dream as a sports reporter for the paper.
"The people who made our newspaper are people we felt we knew, even if we had never met them before", Benjamin Wilson said. Twitter CEO Jack Dorsey has pledged Twitter would work to make sure it becomes a healthier environment for users - at the same time abuse on Twitter intensified during and after the presidential election.
At the White House, spokeswoman Lindsay Walters said: "There is no room for violence, and we stick by that".
In a joint statement, the groups say the tragedy "tears at our hearts, tugs at our compassion and calls fourth our fears for the safety of all those on the front lines of truth, accountability and journalistic pursuit".
Trump is due to campaign next week in Montana on behalf of Republicans including congressman Greg Gianforte, who pleaded guilty to assaulting a Guardian reporter a year ago after lying about it to police.
Court documents and social media posts written by Ramos paint a portrait of an angry, frustrated man fuming about how he'd been mistreated and maligned.