Gun designer Ernst Mauch poses with an Armatix iP1-Pistole in July at a shooting range at Armatix headquarters in Unterfoehring, near Munich. (Sebastian Widmann/For The Washington Post)

Ernst Mauch, the engineer behind some of the world’s most lethal firearms, has abruptly left the German company where he developed a controversial “smart gun” that was introduced in the United States last year.

In his first interview since he left Armatix several weeks ago, Mauch declined to give an exact reason for his departure, but he hinted at disagreements there.

“I am a man making no compromises,” he said from his home in Dunningen, Germany. “I want to walk through my life with a straight and honest backbone.”

Executives from the company, which is based near Munich, would not comment on the circumstances of Mauch’s departure. Financial records reported to German authorities show Armatix has recorded more than 14 million euros in losses since 2011.

Mauch’s separation from the company could present Armatix with a significant setback in its effort to market the world’s first smart gun, which has been met with fierce resistance in the United States by gun rights advocates who fear that the technology will be mandated. Stores in California and Maryland both canceled plans to sell the gun after vehement protests.

Mauch, 59, is the designer of several famous high-powered weapons, including the rifle reportedly used by U.S. Special Operations forces to kill Osama bin Laden. He was seen by Armatix executives and smart-gun proponents as a crucial frontman for the effort because of his long career in firearms.

“The idea of a smart-gun maker who has lots of experience making guns is intriguing because he’s not just some fly-by-night guy trying to do this,” Rabbi Joel Mosbacher, a member of a community group pushing manufacturers for better gun safety, told The Washington Post last year.

In an interview Wednesday, Mosbacher said: “Certainly we’re concerned. But I don’t know that it bodes a death knell for the industry. I hope it doesn’t.” His group, the Metro Industrial Areas Foundation, is holding a smart gun fair in New York later this month that he said Armatix still planned to attend.

Mauch began developing smart guns late in his career after feeling a sense of guilt that guns he designed had been used in crimes and by children to accidentally kill one another.

“It hurts my heart,” he said last year. “It’s life. It’s the lives of people who never thought they’d get killed by a gun. You have a nice family at home, and then you get killed. It’s crazy.”

Mauch’s solution, the iP1, can be personalized so it only fires if the gun’s rightful owner is wearing a special watch connected wirelessly to the weapon. This was his way of bringing what he called “dumb guns” into the digital age.

He had recruited electrical engineers, gunsmiths and a few old contacts in the industry to work with him.

“This is the beginning of a new generation of weapons, which makes people think I am crazy,” Mauch said. “Anyone can make a gun or a pistol. But if the potential is here to make it safer, we have to do it. We absolutely must.”

But many in the industry branded him a traitor for pushing the technology.

When Armatix introduced the gun in the United States last year, there was controversy on both coasts.

The Oak Tree Gun Club in Southern California faced a furious backlash on online forums and social networks after its owner said he was working with Armatix to sell the gun.

The owner later denied that was true despite pictures of the gun for sale in the store.

A few months later, the co-owner of Engage Armanment in Rockville said he would sell the gun, and within hours he too was lambasted by gun rights advocates. He quickly canceled plans to sell the gun.

Much of the animus stems from a New Jersey law requiring that only smart guns be sold in the state within three years of a smart gun being sold anywhere in the country. On Wednesday, N.J. Advance Media reported that lawmakers in Trenton were beginning talks about getting rid of the law.

Armatix has continued to recruit dealers to sell the gun. A recent story in Fortune magazine said that a dealer in Nebraska was marketing the iP1 online to other dealers to then sell to customers. The online dealer would not say how many he had sold, and the company declined to comment on U.S. sales.

Anne Midgette contributed to this report.