Millie Dorsey, Mary Houston’s sister, left, and Lillian Wilson, Houston’s daughter, are seen on the front porch of Houston’s house on Friday in Washington. (Bill O'Leary/The Washington Post)

On Monday, 75-year-old Mary Houston was enjoying breakfast with her husband at a soul food restaurant in Shaw when she went to the restroom and never returned. Her body was found Wednesday a few blocks from her home in Northeast Washington’s Brookland neighborhood.

Her relatives thought Houston, who had Alzheimer’s, had tried to walk the two miles home and collapsed and died along the way. But their pain grew deeper Friday when D.C. police told the family — which had long been planning a Mother’s Day celebration — that Houston had been strangled and beaten.

“We were dealing with the fact she was found dead,” said her sister, 63-year-old Millie Dorsey, who lives in Florida and flew to Washington on Wednesday. “We thought she had fallen, or had a heart attack from getting tired. We were dealing with that. But now we learn she was killed. We’re not dealing with that too well.”

To everyone but her closest relatives, Houston was “Miss Mary,” the wearer of big hats, big jewelry and orange clothes. She was a District government worker for a quarter-century, an avid dancer and prolific shopper, a Sunday church­goer, the mother of three and grandmother of many. Police have not made any arrests, but her sister does not believe robbery was the motive; she said that whoever killed Houston didn’t take her jewelry or money.

Capt. Robert Alder, head of the D.C. police homicide unit, said detectives are trying to trace Houston’s path from the restaurant using surveillance videos. He said her body was found by a construction worker in the basement of a warehouse in the 800 block of Channing Place NE.

Mary Houston (D.C. Police)

The rowhouse Houston shared with her husband, Douglas, filled Friday with grieving relatives who had been planning a festive home-cooked Sunday meal and now instead prepared for a funeral. They came from Maryland, Florida and South Carolina, sharing old stories but too angry for now to cry. “For somebody to do this to such a lovely woman is disgraceful,” Dorsey said.

A few summoned courage and took a short walk from Houston’s home on 10th Street Northeast. They turned onto Evarts Street, then onto Reed, where the neighborhood suddenly transforms into a gritty industrial grid — sagging steel shells sharing space with auto shops and lots guarded by dogs and chain-link fences. Off Reed is the 800 block of Channing, a wide alley bracketed by empty warehouses scarred by graffiti. Houston’s body was found inside one, adjacent to a playground in the back of a private school that fronts Rhode Island Avenue, in sight of elevated train tracks for Metro’s Red Line.

Houston grew up with three sisters and a brother in Salters, S.C., a rural town of about 3,000 with a church and a liquor store roughly 100 miles from Columbia and an hour’s drive from the coast. She moved in with relatives in Washington at the age of 18 to experience life in the big city. She met her husband, and the couple moved into a red-brick rowhouse with a peaked roof in 1976.

Houston arrived the same week as one of her neighbors, Alberta Merriwether, and the two quickly became friends. Their children played together, and they took breaks chatting outside or on their porches on hot summer evenings. Both had jobs — Merriwether taught kindergarten, and Houston processed food stamp claims. They shared rare downtime.

“Mary was always very pleasant, just as nice as you could be,” Merriwether said. “I don’t believe that Miss Mary ever said a cross word.”

Houston liked to travel, to walk and to work, but Brookland was her little world, with her house at the center. She went to church a few blocks away at Israel Baptist. Bored with retirement, she took a job as receptionist at Old Town Trolley Tours, which has its District office on Reed Street, two blocks from Houston’s house and just up the street from where she was killed.

For eight years, until her Alzheimer’s became too advanced about two years ago, she sat a reception desk and fielded calls from prospective tourists.

She did more than book tours on the familiar orange trolleys and duck boats. “She told people that they should come here and that they would enjoy it,” said Eric Holmes, operations manager at the D.C. branch. “She was an ambassador for the entire city.”

Callers frequently asked Houston whether the city was dangerous. The small-town girl with the big city know-how “always told them it was safe,” Holmes said. “I can hear her saying that right now.”

He said his staff is in disbelief. “We can’t fathom that anything bad could happen to that woman,” he said. “She had family over there, at her house, and she had family here.”

Like everyone else, the first thing Holmes recalled about Houston was the way she dressed. Hats and jewelry. Always. She came to work dressed for church. She went to church dressed even better.

“Snazzy,” said Holmes, her boss.

“Beautiful,” said her neighbor, Merriwether.

“Orange,” said her sister, Dor­sey.

Houston’s style was distinct. “You could never be too bright, and you could never wear too much jewelry,” said her daughter, Lillian H. Wilson, who lives in Fort Washington.

Monday’s breakfast outing with her husband was part of what the couple lovingly called their daily “date night.” Merriwether said Douglas Houston doted over his ailing wife, and they were rarely seen apart. “If you saw him, you saw her,” she said.

Relatives said Houston had wandered off in the past but had always returned home. She might have forgotten a name or two, Merriwether said, but “she knew her address.”

That Houston was found dead in her own neighborhood makes it all the more difficult for her family. Said Wilson, “She almost got home.”

Magda Jean-Louis and Victoria St. Martin contibuted to this report.

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