The ghost smolders.

She melts snow. Erik Swanson has seen this more than once. At first, the young honor guard officer at Fort McNair couldn't figure it out. It was a path two feet wide, a foot deep in the snow, right down to the bare grass, maybe 300 yards long. No shovel had dug it. It just ... appeared.

"There are no pipes or anything else below it," he said. Nothing to explain it, except this:

The spectral swath, Swanson discovered, coincided precisely with the path of her final walk, from the jail in which she was imprisoned to the gallows from which she was hanged for the ghastliest crime of its time. A crime many believe she did not commit.

Why wouldn't she smolder?

The ghost weeps. The ghost begs for help.

Army Capt. Dave Osborne swears he heard her outside his window. He lives at Fort McNair, in the very building that had once been her prison. In the pre-dawn hours on Abe Lincoln's birthday 1989, he says he heard a woman's whimpers outside his window.

"It started off softly crying, 'Help me, help me,' " Osborne told the Army Times this month. "Then she began screaming, 'Oh no, help me, help me.' " He raced outside, but no one was there.

The ghost paces.

Laurie Verge, historian for the Maryland-National Capital Park and Planning Commission, used to hold meetings in the Clinton home where the ghost once lived.

"When I was there at night, I got a very eerie, uneasy feeling, the hair on my neck would stand on end. I can't explain it."

One night a few years ago, she says, she and four others were meeting in a room on the second floor when they heard the front door open. Then loud thudding footsteps, the kind that might be made by clod-hoppy 19-century woman's boots, a big woman's boots, pacing the hall, stopping in the middle of the house. Moving no farther.

The five people crept downstairs. No one there. Nothing disturbed. Except their peace of mind.

She was the first woman executed by the United States government -- her neck snapped on a gallows built for the occasion in a courtyard of the Washington Arsenal Penitentiary, which is now Fort McNair. Mary Jenkins Surratt, a strapping widow of 42 and the owner of a boardinghouse on H Street, was convicted and condemned as a co-conspirator in the assassination of Abraham Lincoln.

It is said that a person who dies violently under the shadow of unresolved circumstances is remanded to a certain purgatory -- a disturbed spirit in the realm of the living -- waiting for a time when the truth behind his death is revealed. Mary Surratt qualifies as a ghost of exceeding prominence, as her innocence, or at least the degree of her guilt, remains stubbornly debated well beyond a century after her death. And, it is said, her spirit is restless.

For years, there has been ghost talk at Fort McNair. There have been reported sightings -- a black-clad figure, bound hand and foot as Surratt was at her death, but now moving effortlessly, her hooded head drooping unnaturally close to her shoulder. A military couple has told Army Times that a pane of glass in a window of their home fogs up mysteriously at night; this, they were informed, was the selfsame window from which young Anna Surratt watched and wept as her mother dropped to her death.

It was the most famous hanging in American history. Detailed accounts remain:

It was July 7, 1865. Mary Surratt was led to the scaffold outside the prison building barely able to walk, the combined effects of debilitating fear and the shackles around her ankles. Practically carried up the steps to the platform, she stood weakly under the blazing sun as the noose was adjusted around her neck. She was able to see beyond the rope her own coffin waiting below and a freshly dug hole in the ground yawning to to greet her. She gasped at the sight and begged her captors, "Don't let me fall," seconds before the floor dropped from beneath her.

The portraits of a stern, hardened woman in the two photographs of Surratt known to exist seem to reflect her character -- a woman who had lived a difficult life and who thought in extremes. Sent as a young, fatherless girl to be educated by the Sisters of Charity in Alexandria, she became a convert and a relentless Roman Catholic proselytizer. She also had an abiding kinship with the Southern secessionist movement all of her adult life -- an association that, justly or not, would lead to the noose.

At the age of 17, she married John Harrison Surratt, a rabid secessionist and debt-ridden drunk. They purchased 287 acres in Prince George's County and built a home they also used as a tavern, a hostelry, a post office and a polling place in a town that would become known as Surrattsville (now Clinton). Located in a county with deep-seated Southern sentiments (Lincoln received one vote there in the 1861 election), and with John Surratt's vocal opposition to Union policies (he owned seven slaves), the establishment became a speakeasy for those sharing similar attitudes. There is also ample evidence that the Surratt residence, just 12 miles outside the capital, became a safe house for the flourishing Confederate underground.

When John Surratt died in 1862 his wife was left with the burdens of an encumbered farm and other legacies of her ne'er-do-well husband. With her elder son, Issac, serving in the Confederate Army, and with John Surratt Jr. occupied as a Confederate courier, it proved nearly impossible for Mary to keep the family business afloat. She decided to rent the Surrattsville property to a former D.C. policeman, John Lloyd, and move to a boardinghouse in Washington that had been acquired by her husband years earlier -- a fateful move.

Actor John Wilkes Booth was a frequent visitor at Mrs. Surratt's. The impassioned, secessionist actor had allied himself with Surratt Jr. and they set about forming a plan to kidnap the president. The house became a meeting place for those recruited to carry out the plan they hoped would effect a better settlement for the South near the Civil War's end. The kidnapping scheme, a rather inept effort, failed miserably, and Booth's intentions soon turned to murder. It was carried out on April 14, 1865.

After the assassination, with the war still being waged, an immediate restoration of stability was the paramount goal of Secretary of War Edwin Stanton. He sought swift justice. By some accounts, Mary Surratt was a bit player swept up in the frenzy. Booth, the leading actor, was already dead -- shot in a barn by Union troops who had tracked him down to Bowling Green, Va., after his escape from Ford's Theatre. The government quickly pressed its case against the supporting cast.

The military court heard testimony from Lloyd that Mary Surratt had instructed him to expect travelers to arrive on the night of April 14, and to provide them with supplies, including field glasses she had delivered herself and guns hidden at the house by Surratt Jr. The two men who arrived were Booth and David Herold, a co-conspirator. There was also testimony from various tenants at the H Street boardinghouse that Mary Surratt had met there regularly with the conspirators. It was enough to convict her.

The speedy trial left many questions. Was Surratt really an active participant or merely at the periphery of the plot? If she was involved in the kidnapping scheme, did that make her liable for Booth's decision to murder? Could it be that she was charmed by the handsome actor and unwittingly assisted him, or -- as some supporters claimed -- that she had merely met with some of the other conspirators to preach her religion? In a court document, Lewis Powell (a k a Lewis Paine), who failed in his mission to kill Secretary of State William Seward, attested to her innocence. On the other hand, George Atzerodt, who was slated to kill Vice President Johnson, stated that she was fully involved. Both hanged with her.

Judge Advocate General Joseph Holt, who served as a government prosecutor, reportedly became a recluse after the trial. Some Surratt supporters claimed that he hid from President Johnson the military commission's recommendation that she be given life imprisonment because of her age and sex; in any event, Johnson said he never saw the recommendation before he approved the hanging.

Surratt Jr., who had escaped to Italy after the assassination and was captured two years later, was tried and acquitted on charges nearly identical to his mother's. Samuel Mudd, the doctor who had set Booth's broken leg, was given a life sentence for his role in the plot. He was pardoned four years later.

Today, there are more than 900 members of the Surratt Society, which operates a museum (staffed with volunteers) at the restored Surratt home/business in Clinton.

"It's addictive," says Laurie Verge, the state historian. "Everyone is looking for that one bit of evidence that will settle once and for all the big question."

In the meantime, the ghost smolders.