LAS VEGAS — The scene of carnage this time was a flat 15-acre parcel of land without any permanent structures. It is a rectangle of blacktop surrounded by busy streets, including the famous Las Vegas Strip. Marketed as “Las Vegas Village” the past couple of years, it has the feel of a small county fairground. There are a few white corporate-style tents on its edges, and a large concert stage at the south end. It has been used to hold small music festivals and rodeos.

On the night of Oct. 1, crowded with about 22,000 people attending a country music concert, it became a kill zone. And one of the many questions left in the wake of the deadliest mass shooting in modern American history is what to do with the place.

From Columbine to Sandy Hook, Mother Emanuel to the Pulse nightclub, those left behind have had to grapple with the murder scene, and the difficult balance between looking back and moving on. Some decided to tear down the buildings where the killing was done; others remodeled and reopened them, or just moved right back in.

Las Vegas poses some unique issues, though: There is nothing permanent about the concert venue, and the killer was not in the same place as the victims. The gunman, Stephen Paddock, fired from the 32nd floor of the Mandalay Bay Resort and Casino, about 500 yards away across South Las Vegas Boulevard.

The two sites on opposite ends of the massacre are both owned by MGM Resorts International, which will have to decide what to do with them.

Barbara Poma, the owner of the Pulse nightclub in Orlando, where 49 people died in a shooting in June 2016, said the decision will not be easy. “There are so many feelings and emotions involved, and those feelings change over time,” Ms. Poma said. “No rash decision should be made at all.” She said she is still in discussions over what to do with Pulse.

There are no events scheduled at Las Vegas Village, and the gunman’s hotel rooms at the Mandalay Bay remain sealed off as a crime scene (though other rooms on the 32nd floor are in use).

Sheriff Joseph Lombardo of the Las Vegas police said on Monday that investigators were still working at both sites. He said the police continued to seek information about Mr. Paddock’s motive, and had visited the gunman’s property again in hopes of uncovering new information.

“This individual purposely hid his actions leading up to this event,” Sheriff Lombardo said. “And it is difficult for us to find the answers to those actions.”

People who have been through the process of dealing with shooting sites after the police are done with them know that difficult and delicate discussions will loom for MGM and for everyone with a deep interest in what happened and what happens next.

“Where the victims were, that is relatively easy to deal with, in that what happened there was a tragedy, with independent acts of heroism and solidarity,” said James Hawdon, a professor of sociology and the director of the Center for Peace Studies and Violence Prevention at Virginia Tech. “It would be easy to transform, because there is nothing there. It’s basically a vacant lot.”

Trickier, he said, will be the gunman’s perch in the hotel — a spacious suite with wraparound views and an adjoining standard room, where Mr. Paddock shot through an entry door at a security officer and was later found dead from a self-inflicted gunshot.

“The hotel rooms, it’s hard to think of anything socially positive from the space,” Mr. Hawdon said. “That space was purely evil, the actions in that space. To me, you somehow try to make it unrecognizable. You want to try to make it devoid of meaning related to the tragedy.”

Mr. Hawdon’s office at Virginia Tech is in Norris Hall, the building where 30 of the 32 victims of a 2007 mass shooting were killed in two second-floor classrooms and a hallway. After much discussion, Virginia Tech decided to remodel the space into laboratories and offices, including Mr. Hawdon’s.

“People have asked me, ‘Does that bother you?’ ” Mr. Hawdon said. “I say no, because what that space represents is resilience — not the violence, but the response that followed the violence.”

Situations and perspectives vary, of course. Sandy Hook Elementary in Newtown, Conn., was torn down after 26 people, including 20 children, were killed there in 2012, and a new school was built to replace it.

At the Emanuel African Methodist Episcopal Church in Charleston, S.C., the basement room where nine church members were shot dead in 2015 remains open, almost exactly as it was before the massacre.

Likewise the Sikh Temple of Wisconsin in Oak Creek, which reopened its doors to the public four days after a gunman shot and killed six people there in 2012.

Balhair Dulai, the temple’s president, said in an interview that the initial goal was to show unity and a lack of fear in the face of violence. The temple added extra layers of security, but it is otherwise unchanged, he said, except for a bullet hole in a door frame in the lobby.

“Just because something happens in a place, it doesn’t automatically turn it into a memorial,” Mr. Dulai said. “What really lives is what lives inside you. It just happened to be there. But we should not glorify that in any way.”

Places of business may be viewed differently than houses of worship. Salon Meritage in Seal Beach, Calif., was gutted and renovated after a shooting spree there in 2011, and reopened about a year later. In Tucson, Ariz., where six people were killed in front of a Safeway supermarket in 2011, the store reopened a week later. Many people in Aurora, Colo., were furious that the movie theater where 12 people were killed in 2012 reopened six months later with just a few cosmetic changes.

When the scene is in a school, the choice more often is to demolish and replace it. At Columbine High School outside Denver, where 13 people were killed by two student gunmen in 1999, the library where much of the carnage took place was replaced by an atrium, and a new library was built elsewhere. Umpqua Community College in Roseburg, Ore., is rebuilding Snyder Hall, where nine people were killed in a classroom in 2015.

The conundrum of what to do with a mass murder scene has been felt acutely in Orlando.

“When Pulse first happened, I remember telling myself, ‘Tear it down, tear it down, tear it down,’ ” said Ms. Poma, who owns both the 4,000-square-foot nightclub building and the land where it stands. “I wanted it, I needed it, gone — it was so awful, I wanted it to go away. And now, 16 months later, people settled down, and some people are like, ‘No, it’s part of our history. You shouldn’t take it down.’ ”

She has no interest in reopening the nightclub, the way the Bataclan concert hall in Paris did a year after 90 people were shot and killed there in 2015.

The city of Orlando offered to buy the Pulse property, but Ms. Poma decided instead to form the nonprofit OnePulse Foundation, whose main mission is to erect a memorial and museum there. The foundation has sought input from survivors, the families of victims, the police and emergency workers, and the general public on questions like whether to demolish the building.

“It’s part of our history — not just Orlando’s history, but American history,” Ms. Poma said. “Those tragedies cannot be erased, and their lives should not be erased. They were taken, and you can’t let that happen in vain.”

Her advice to MGM is to take time to assess what to do. But at some point, the company will have some difficult decisions to make.

Should it simply close off the gunman’s rooms indefinitely? Should it remodel them with new carpet, furniture and walls and reopen them to guests? Should it renumber the rooms, or even the floor, to disguise the place’s sordid history and deter the morbidly curious?

As for the 15-acre lot across the street, the company must decide whether it can ever be used again as an open-air venue with large crowds. And over the longer term, it must decide whether a memorial, a museum or something else should be erected there to honor the victims and signify the history.

Or, this being Las Vegas, the land could be developed, with a giant casino taking its place among the others on the Strip, leaving no visible trace of what had been there before.

No matter what is decided, though — no matter how much the landscape and the scene may be altered — what happened there will not be erased.