Photo provided to China Daily

"I encountered a conflict of interest when helping friends as a cop," he says. "I didn't want people to say I was using public power to serve personal interests."

Meng and his detectives－mostly former policemen or academy or law school graduates－have since solved more than 1,500 cases. His first involved a woman whose husband often mailed money to another woman. She suspected they had a child.

Meng began with a letter the woman wrote to the man and the child's birth certificate. He found they did have a baby－but the infant died days after it was born. The woman had divorced and lost her job, and was cheating the man out of money.

"I didn't get much for that case," he recalls.

"But I was really happy the woman said I'd saved her marriage. I really hate when people say private detectives just reveal mistresses and invade privacy. Some victims are really helpless and deserve assistance and compensation."

Meng has handled more business disputes than extramarital affairs. Infidelity accounts for a third of his dealings. While business is booming, it compels "dancing with danger".

"Not everyone can do this," he says. "It's a highly demanding profession. It requires wisdom and courage. Investigation subjects often turn out to be mobsters. You face payback if you upset them."