OMAHA, Neb. -- Infidelity cases are becoming big business for private detectives, PIs told television station KETV, as more people go to longer lengths to catch cheating spouses.

Brett Pippin, with Armored Knights Inc., said infidelity investigations make up more than half of his case load. On one Friday night, the station rode along as Pippin sat in the shadows, waiting to catch a cheating spouse. For several weeks, Pippin allowed KETV to follow him on the same case.

"I'll just follow him all night and see what he does," Pippin said. "From what I'm being told from the client, he may have two or three other women."

The client is a woman who asked not to be identified.

"I wanted to make sure that I saw him with somebody else. In order to believe it 100 percent in my head that it's actually happening," she said.

"She thought that he was probably cheating on her, but she didn't really have proof, and then once everything came to light, people started telling her things," Pippin said. "That's usually how it works."

Pippin is director of security and investigations for Armored Knights, a company well known for its armored car and security systems. But nearly 70 percent of its investigations involve matters of the heart.

"I do stay pretty busy," Pippin said.

Hiring a private investigator to spy on a spouse may seem like an extreme measure, but family therapist Dr. Mark Ziegenbein said that when relationships start faltering, trust is often the first thing to go.

"You don't really know what your spouse may be doing or not doing and you want to find out," Ziegenbein said.

The doctor said it's healthier for couples to discuss those issues, but he's not surprised so many people spy on their spouses.

"You don't have to risk talking about things, or risk exposure to friends and family," Ziegenbein said. "You can go to a store and get the equipment you want to use, and I think more people are taking that option."

Pippin said that people who do their own detective work could cross a line between snooping and stalking. PIs have to be tested on all of the trespassing and privacy laws to get their licenses.

Pippin said that in his job, he looks for patterns.

"If you follow somebody for an extended period of time, then you start seeing their patterns, and what they really do -- if they go to a bar every night, or some mistress or whatever," Pippin said.

Pippin will secretly attach a global positioning system to his suspect's vehicle.

At 5 a.m. on a Wednesday, Pippin made the GPS drop on the man's car. It's a legal tactic, made even more solid by the fact that the suspicious wife's name is on the title, and she signed off on the GPS plant. Pippin said planting the bug is a risky mission that he'll have to undertake each time the batteries die.

"We've got him covered, right now. We'll know where he is all the time," Pippin said.

Pippin will spend hours or days tracking his man, hoping for evidence he can deliver to his client. He said the mission takes strong instincts and a knack for blending in.

"People who are cheating are always looking around," the detective said. "I think that's the biggest thing. You learn how not to get caught."

Pippin is still in the middle of the investigation KETV followed.