A group of demonstrators has parked cars on top of the new Black Lives Matter mural on Hamilton Avenue in Palo Alto, guarding it against both the elements and cars and concerned that the image of a convicted police killer could be erased, they said Wednesday.

The volunteer artist and allies noticed on Wednesday morning that the city had taken down street barricades that had kept traffic off of the mural, which spells out the words "Black Lives Matter" in block letters filled with colorful designs and memorials to the struggle of Black people in America.

Tire tracks had already begun to streak the mural by Wednesday evening. About 10 demonstrators parked three cars on the mural, one each at either end and one in the middle. Motorists were still able to drive in the right-hand lanes, which are not covered by the artwork.

The group, concerned the latex-paint mural might wear away, had wanted the city to paint a protective layer over the artwork. City Manager Ed Shikada said on June 30 that the city hadn't decided whether it will coat the paintings.

Artist volunteer Matthew Basirico, who helped paint the letter "R," but who was not one of the city's officially commissioned artists for the project, called Mayor Adrian Fine Wednesday about the coating. He said Fine asked him to email him, but Basirico said he doesn't want to engage in an email exchange.

"I plan to be out here until we negotiate putting the protective barrier down," he said.

Fine said in an email on Thursday morning that the mural was intended to be temporary.

"I think it came out beautifully and is an important symbol for Palo Alto. We also have real, difficult, and long-term work to do in addressing structural racism. I repeatedly asked the city to find a way to preserve the mural for longer, but the staff doesn't believe it is feasible," he said.

Basirico said he also strategically parked his car on top of the "E" in "Matter," an artwork that has generated controversy because it contains a depiction of Joanne Chesimard. The National Police Association has asked the city to remove Chesimard's image, who escaped prison in 1979 while serving time for the 1973 killing of a New Jersey State Police trooper, according to a petition by the police association.

Chesimard, also known as Assata Shakur, was a member of the Black Liberation Army in the 1970s, a group that had killed 13 police officers, according to the police association. She and two others opened fire on two troopers during a traffic stop. One of the troopers died and the other survived the gun battle. Chesimard was later captured and convicted of first-degree murder and multiple other felonies. She was granted political asylum in Cuba after escaping from prison. She remains on the FBI's Most Wanted list, the association said.

"If it is not possible to imagine putting a 17' tall mural of nurse Richard Speck (a mass murderer) in front of a hospital or putting a 17' tall mural of Dan White, who assassinated San Francisco Mayor George Moscone and Supervisor Harvey Milk, in front of a mayor's house, the atrocity of the celebration of a fugitive convicted cop killer in front of Palo Alto's City Hall is equally reprehensible. For law enforcement required to enter the building is there any description other than a hostile work environment?" the association wrote

Fine said he was disappointed to learn about the inclusion of Joanne Chesimard in the mural.

"In no way does the city condone or support violence. But I'm also not interested in removing her image. Part of this process is allowing new voices to speak up, and that my be uncomfortable, but that's one of the great things about art," he said.

The artist who painted the mural containing Chesimard's image, CeCe Carpio of Oakland, is a disaster worker by day and a painter, said in an email that as a woman of color, an artist, a muralist, and as a cultural worker, she reclaims public spaces and creates larger-than-life images to tell stories of collective experience.

"In our current time, when the Black Lives Matter movement continues to be on the rise, I feel it is imperative that we participate and show solidarity with our Black communities. The fight for Black liberation has paved ways for us to be here. It is our responsibility to continue to defend Black Lives and support Black resistance," she said.

"As a resident of Oakland with its rich history of this movement, birthing the Black Panther Party, it is important to me to share this history with young people like my niece because its legacies give us hope today. The Black Panther Party created over 65 survival programs including the breakfast and lunch program for school children, free health clinics and sickle cell anemia testing. They advocated for health care, affordable housing and participated in political elections. Their demands still ring true for us all. Demands that continue to be made by movements across the world."

Carpio felt it was important to represent the "words and wisdom" of Chesimard, who she said has been a political refugee since 1979. The mural contains a quote from Chesimard that reads, "We must love each other and support each other," Carpio said.

"Assata was a target of policing and COINTELPRO, and is still a target of the policing and the U.S. government. They see her involvement with the Black Liberation movement as a threat to the status quo. Just as they see the movement to defend Black lives as a threat to racial capitalism and white supremacy," she said.

Meghan Horrigan-Taylor, the city's chief communications officer, said in an emailed statement Wednesday night that the mural is "one aspect of a larger city dialogue taking place on race and equity and connects to the city's thoughtful conversations on the role of policing.

"The mural is temporary," Horrigan-Taylor said. "In no way does the mural take away from the value we have in our police officers who serve our community every day. Temporary art is a means of expression on difficult issues and the Black Lives Matter mural is thought-provoking and is inspiring conversation."

On Thursday, Horrigan-Taylor added in an email that a mural volunteer, not a commissioned artist, requested the city look into a sealant. Staff considered application of a sealant and concluded that it could change the color of the artists’ work, cause a safety hazard when the sealant gets wet due to adding a slippery surface, among other considerations. Because of these issues, it was decided to not apply a sealant.

From the beginning, the city's intent that the mural would be a temporary installation was communicated to the artists and the broader community as a temporary installation, she said.

Editor's note: In a previous version of this story, Basirico claimed that artist CeCe Carpio was negotiating with City Manager Ed Shikada to keep her mural intact. Horrigan-Taylor disputed that claim.