The hills in Clarks Glen are gently rolling, the homes McMansions. And the lawns are mowed to the near-perfection a country club groundskeeper might envy.

It's the very model of affluent suburbia, hardly a place where anyone thinks the man next door would be stopped by customs agents on his way to China with the makings of missile detectors in his bags.

But appearances can be deceiving.

Zhenchun "Ted" Huang, a longtime resident of the Clarksville subdivision in Howard County, pleaded guilty this month to federal charges that he tried to fraudulently obtain electronic devices that can be used in fabricating missile detectors and other high-grade military equipment.

The U.S. government controls the export of such "dual-use" devices, but Huang, a Chinese national, had two in his luggage on May 8, 2006, when customs agents stopped him at Chicago's O'Hare International Airport. He was about to board a flight to his native land.

Ten months later, a Maryland grand jury indicted Huang in absentia. He was arrested in London last year after living several years as a fugitive.

Huang, 51, agreed to a plea deal and remains in custody pending sentencing in October.

In Clarks Glen, the development where he lived for at least eight years, former neighbors were astonished to hear the news. They saw Huang, an electrical engineer, as anything but the cloak-and-dagger type.

Instead, they said, he was a taciturn man who mowed his lawn once a week, whether it was needed or not, and rarely socialized.

"We lived next to him for at least a year, and he never said a word other than 'hello,' " said Gayatri Potluri. "We thought it might be due to a language barrier. We didn't know what his job was. This is a shock."

Huang's former wife and his son lived with him in the neighborhood for several years, Potluri said, adding that they also seemed to have few visitors and little contact with neighbors.

The agencies that tracked Huang over the years — officials from the FBI, Customs and the Department of Commerce, among others, were present at an announcement of the plea deal — clearly saw a different Ted Huang than his neighbors did.

The two charges against Huang are impersonating a federal employee and obstructing justice, but intelligence analysts said the case has all the hallmarks of a long-term covert operation.

Huang has lived in the U.S. since the 1990s. He earned a doctorate in electrical engineering from the State University of New York at Buffalo in 1993, then accepted a succession of positions in academia and private industry.

His area of expertise, optoelectronics, deals with the design and fabrication of electronic devices that detect and control light. From 1995 to 2001, he used it in his work as a contract scientist at Goddard Space Flight Center, a division of NASA.

He left that position in 2001 to start Allray Inc., a firm that designed and made high-powered light-emitting diodes (LEDs) and other light-related technologies. He based its operations in China but often listed the Clarks Glen home as the business address, according to charging documents.

The details of the case are, at times, as complex as Huang's line of work.

In 2003 and 2004, according to the plea agreement, he contacted three American companies to try to acquire semiconductor products known as cadmium zinc telluride wafers and mercury cadmium telluride wafers.

The wafers have civilian uses but can also be used to enhance night-vision technologies and create high-end missile detectors — which is why the federal government requires special permission to export them to certain nations, including China.

While trying to acquire the wafers, Huang tried to evade suspicion by presenting himself to potential vendors — falsely — as a scientist who still worked for NASA, according to charging documents.