The mystery that for weeks unnerved this quiet Capitol Hill neighborhood began with a warning placed on a nanny's windshield.

"I know you are misusing this visitor pass to park here daily," the April 4 note read. "If you do not stop I will report it, have your car towed and the resident who provided this to you will have his privileges taken away."

Baffled, the young couple the nanny worked for sent out a message on the community email group asking for the note's anonymous author to contact them. No one came forward.

Instead, two days later, the nanny's license plates were stolen from her SUV, according to charging documents. Two days after that, another plate was stolen. Then, in late April, the thief struck once more — but this time the couple caught him on a video camera they had mounted inside their home's front window.

And the alleged culprit? In an only-in-Washington story, police identified him as Bryan Whitman, a top Pentagon official who has worked at the Defense Department for more than two decades.

During a 2002 panel discussion, Pentagon spokesman Bryan Whitman spoke about the inherent tension between the military and the news media. (C-SPAN)

After handing over the plates to police and being charged with three counts of misdemeanor theft, Whitman, 58, agreed to a deal on Tuesday that would lead to the case's dismissal if he pays $1,000 in restitution, performs 32 hours of community service, remains out of trouble for the next 10 months, and stays away both from the nanny and the woman for whom she works.

The strange series of events could be viewed as the latest example of the District's perpetual parking wars, except residents say parking isn't a problem on their streets and that many babysitters use the visitor passes.

That's perfectly legal for nannies to do, said Terry Owens, a spokesman for the District's Department of Transportation.

Whitman, who declined to comment, is the highest-ranking career civilian in the Defense Department's public affairs office, according to his former supervisor, Price Floyd. Whitman's title: principal deputy assistant secretary of defense for public affairs.

In that role, his LinkedIn page says, the retired Army officer "personally advises the Secretary of Defense and senior leadership on the public impact of proposed policies, programs, operations, and activities of the Department."

During much of the wars in Iraq and Afghanistan, he was one of the Pentagon's top spokesmen and a familiar figure to dozens of Washington reporters. From 2002 to 2010, according to his lengthy work biography, "he was responsible for all aspects of media operations for the Defense Department."

On Wednesday, Whitman's colleagues in the public affairs office declined to say when the department became aware of the charges, if they were investigating his alleged misconduct, whether the case will impact his career or security clearance and how much he gets paid.

"I have a hard time accepting this. It just doesn't — wow," said Floyd, who worked with Whitman in 2009 and 2010. "This whole situation does not make sense to me. It's not the Bryan I've known and worked with and respected."

A former political appointee who also worked at the Pentagon was just as stunned.

"I mean, I'm speechless, I don't even know what to say, frankly," he said. "I've always found him to be a good guy. I relied on his advice a lot."

Both described Whitman as meticulous, organized and professional. Another former senior defense official and reporters who know him said he is a stickler for following the rules.

Whitman — who according to two former Pentagon colleagues makes at least $150,000 a year — has lived on First Street SE on Capitol Hill for about 20 years, court records show. Beyond a fenced courtyard, a brick staircase leads to the front door of his tidy rowhouse, valued by city tax assessors at nearly $900,000.

Surrounding streets are lined with wooden benches and American flags, and Ginkgo trees tower over carefully manicured gardens. The sidewalks are frequented mostly by dog-walkers, retirees and young parents pushing strollers.

"It's very quiet," said one neighbor. "Everybody is just cordial."

Well, not everybody.

The first sign of discontent appeared atop the nanny's windshield on April 4.

In addition to the note's message, the sheet of paper included a photo of the nanny's decade-old Lexus SUV and of her visitor parking pass. The note was placed on the nanny's front windshield, just next to a guardian angel prayer written in Spanish and displayed on her dashboard.

Both of the license plates from that car were stolen on April 6 — the day before Whitman's 58th birthday.

The homeowners, who along with their nanny declined to comment, reported the crime to police, replaced the plates and paid AutoZone to bolt them on, court records indicate. They repeated this process later that week after the rear plate was stolen again.

It was then, court records say, that the couple went to Best Buy, where they spent $211.99 on a surveillance camera and an additional $105.75 on a subscription to the video service.

The nanny, who cares for the couple's 1-year-old son, also began driving to work in a Honda minivan with plates secured by hefty allen bolts. Both on April 13 and 14, court records say, the video showed Whitman approaching the van and inspecting it.

The child's mother, according to the court records, suspected that he didn't attempt to steal the plate then because "the suspect was not prepared with the necessary tools to unscrew these bolts and therefore he was unable to remove the license plate."

A week later, he returned just before noon, and the charging documents describe in detail how determined he was to unhinge the plate: Parking near the nanny's van, walking back and forth from his car to hers, crouching behind it, leaving, returning, crouching more, walking back to his car, driving away.

The process, from beginning to end, took 47 minutes.

The couple soon realized that Whitman is their neighbor. He lives just around the corner.

On May 2, detectives arrived at his home with a search warrant.

The police "asked whether he wanted to provide the license plates to MPD or have the officers search for the items," the charging documents say. "The suspect consulted his wife and then [said] that the license plates were in his vehicle."

He gave them up.

Even with the charges filed and Whitman ordered by the court not to harass the nanny or her employer, his contact with them didn't end.

On May 5 — the day of his arraignment — the homeowner reported to investigators that he walked in front of her rowhouse. Then, on the night of May 10 until the next morning, he parked in front of their house.

"Out of fear for her safety," court records say, the nanny "has begun to park her car two blocks away from the house of her employer."

Prosecutors asked that a judge bar Whitman from contacting either woman or setting foot on their block, arguing that the nanny couldn't understand his behavior and "she does not know why he is targeting her or what he might do next."

On Tuesday night, Whitman answered his door in shorts and a gray T-shirt as a baseball game played on his living room TV. A reporter asked him if he would discuss the case.

"No," he said. "I don't think so."

As part of his agreement with the government, Whitman has also been ordered to stay away from the family's entire block, except when he needs to access the alley behind his home. There, a wooden fence encloses his back yard.

On the door is a white sign with bright-red letters: "These premises protected by VIDEO ­SURVEILLANCE."

Julie Tate contributed to this report.