Police in the District and Montgomery County say they suspect that the same pair of armed men may be responsible for a spate of as many as 12 street robberies since late November in Upper Northwest and within blocks of the Bethesda-District line near Western Avenue.

Many of the robberies have occurred in the early evening, when people are taking walks or arriving home. The robberies, in an area that includes upscale shops and restaurants, have residents on edge.

A robbery about 7 p.m. Wednesday on Western and Chevy Chase Circle follows that pattern, authorities said.

Samantha Nolan of the Chevy Chase neighborhood in the District said the brazenness of the robberies is “very disconcerting.” Doing three stickups within minutes and then returning to the same neighborhood is “very bold” and suggests that the robbers don’t have much fear, she said.

The robberies come as a housekeeper was sexually assaulted and a mother and teenage son were tied up during a home invasion in Bethesda Wednesday morning. Montgomery County police say the incident involves the same man who committed a Tuesday home invasion in Wheaton. Police linked those incidents Wednesday afternoon, but say they are unrelated to the robberies.

A surveillance video shows a man who could be the suspect in two home invasions in Wheaton and Bethesda. (Courtesy of Montgomery County Police Dept/COURTESY OF MONTGOMERY COUNTY POLICE DEPT)

Before Wednesday night, the most recent related robbery occurred on Tuesday about 9:20 p.m., when a woman walking in the 4100 block of Livingston Street NW was robbed at gunpoint of her purse and cellphone, D.C. police said.

The woman told police she noticed a man hiding in the tree line on the south side of the street. When she tried to cross to avoid him, she told police, the suspect ran to her and robbed her.

The robberies are not like the crimes that targeted iPhones and cellphones last year, police said. The suspects in the recent events usually show guns and have taken purses, briefcases and wallets, police said,

“We can’t say definitely these are all the same suspects because no one has been caught, but there are enough similarities that we are looking on them as linked,” said Cmdr. George Kucik, head of the D.C. police criminal investigations division.

Capt. David Falcinelli, commander of the Bethesda district for Montgomery County, said two robberies on Nov. 22 and Dec. 26 near the Bethesda border with the District also are believed to be part of the pattern. Police are looking at links with at least three other robberies.

The Livingston Street robbery comes after three similar stickups within 30 minutes of one another early Sunday evening in Cleveland Park and Friendship Heights. D.C. police say theythink another four since Dec. 10 also share similar characteristics.

The robbers generally have hit between 6 and 11 p.m, police said. They have usually approached people who are walking alone or getting out of their cars. But there have been incidents in which two people were robbed together.

Victims often have been taken by surprise and sometimes were approached from behind, making descriptions of suspects difficult. “This probably doesn’t take more than 30 seconds,” Kucik said.

From the vague descriptions, police are looking for two black men, both about 6 feet tall and in their 20s to 30s, who mask their faces with a scarf or jacket hood. The suspects have displayed guns in the District incidents, D.C. police say. A gun was shown in at least one of the Bethesda robberies, Falcinelli said.

The robbers usually tell their victims to walk in one direction while they flee in the other. Kucik said they suspect an escape vehicle has been nearby, and have one report of a dark blue car being involved. “But we know people often use stolen cars and switch them out once they get too hot,” Kucik said.

The two departments say they have ramped up police visibility and patrols, but also have taken more covert steps that they declined to detail.

Kucik said police urge anyone who is approached to cooperate. “No one has been injured thus far and we do not want to see that happen,” he said.

Police also are asking residents to be aware of their surroundings and to call police if they see a car or activity that seems suspicious, he added. “Maybe it’s innocent but we would rather make contact with a person and find out there is a legitimate reason for them to be in an area.”

The latest of the unrelated home invasions began about 6:45 a.m. Wednesday when a housekeeper who had just arrived for work in the 9200 block of Bardon Road went outside to move her car and found a man at the front door, police say. The suspect pulled a gun and forced the woman into the house, police said. He then tied up the housekeeper, the homeowner and the homeowner’s son, and assaulted the housekeeper.

The suspect stole a debit card and the keys to the housekeeper’s Ford Expedition, which he used to flee, according to police. The stolen card later was used at a CVS in L’Enfant Plaza in the District, police said.

Detectives linked the Bethesda robbery to a home invasion that occurred about 10 a.m. Tuesday in the 2900 block of McMahon Road in Wheaton. There, a woman had entered her home’s garage when the suspect approached with a gun and demanded money, which the woman pulled from her wallet, police said.

The man then demanded the victim’s debit card, PIN number and car keys, police said. The robber fled in the victim’s car and later used her stolen card at a bank ATM in Oxon Hill, according to police.

The suspect in both robberies is described by police as a black man in his late 20s to early 30s, 5-feet 7-inches tall, with a slim build. He was wearing a black jacket, a sweatshirt with pockets in the front, dark-colored pants and brown-framed eyeglasses, police said. He wore a black ski mask and gloves, police said.

After the Bethesda home invasion, the suspect fled in the gray Ford Expedition with Maryland tags 4AE7450.  The vehicle has a McDaniel College sticker on the rear windshield.

Staff writer Erica W. Morrison contributed to this report.

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