OAKLAND — The Alameda County District Attorney’s Office has declined to file charges against a Southern California artist and teacher arrested last week at Oakland International Airport for wearing a suspicious watch.

A spokeswoman for the prosecutor’s office on Monday did not elaborate on why charges weren’t filed against Geoffrey McGann, 49, of Rancho Palos Verdes.

McGann was arrested at about 7:45 p.m. Thursday after airport security found him wearing a watch that looked like a timing device for an explosive, Alameda County sheriff’s Sgt. J.D. Nelson said.

defense attorney Douglas Horngrad said his client was set to appear in court Monday on the charge but that when the two showed up at Alameda County Superior Court a clerk told them the case had been dismissed. Horngrad said McGann did not have any harmful materials, didn’t intend to harm anyone and didn’t pose a threat to anyone.

He accused Transportation Security Administration and Alameda County sheriff’s officials of “overreacting” and said the prosecutor’s decision “illustrates the unreasonableness of law enforcement’s actions here.”

“It’s something for TSA to be vigilant, but it’s something else to by hypervigilant,” Horngrad said Monday.

Nelson said McGann was wearing a watch on his wrist that had a toggle switch and wires and fuses protruding from it that looked suspicious.

A bomb squad was called to the checkpoint and determined there was no explosive device connected to the watch.

McGann was arrested and taken to Santa Rita Jail in Dublin but was later released after he posted $150,000 bail.

Nelson said even if McGann truly is innocent and didn’t intend to harm anyone, he still thinks that McGann showed “a lack of good judgment” and “was not being very smart” in traveling with the watch.

However, Horngrad said McGann has traveled with the watch before and has never previously been arrested.

The attorney said if McGann had planned to use the watch to detonate a device on the airplane, he would have hidden it instead of wearing it.

Horngrad said the first time McGann traveled with the watch, he showed it to a TSA supervisor at Los Angeles International Airport and the supervisor told him it was OK to wear it on the plane.

He said that when McGann went to the Oakland airport, he “acted consistently with his character, which is that of a commercial artist and teacher.”

McGann “is not an activist or a terrorist,” Horngrad said.

He said McGann has made dozens of the kind of watch he was wearing when he was arrested and said they have “a popular design among people who have seen them.”

Horngrad said any kind of device that keeps time can be used in the making of a trigger for a bomb but that McGann’s watch is handcrafted and “is more art piece than timepiece.”

Horngrad said he plans to file a motion to have his client declared “factually innocent” and will seek to have the arrest removed from his client’s record.

Bay City News Service contributed to this report. Follow Natalie Alund at Twitter.com/nataliealund.