A Shanghai police officer has posed as a mentally ill woman's dead son for five years to protect her from the painful truth.

Jiang Jingwei, 36, met his "parents" for the first time on a television show in Hangzhou, Zhejiang province, after producers received an appeal from Xia Zhanhai to help find him.

Xia lost his eldest son Liang Yu after a gas leak in the family home in 2003. His wife, Liang Qiaoying, was also left paralyzed and brain damaged by the accident.

Over time, his wife regained her ability to move, but mentally she remained deeply anxious and constantly asked to see her son, unaware he was dead. To shield her from the truth, Xia lied and said Liang Yu was working in another province and could not come home.

Seven years later, Xia saw Jiang - who closely resembles Liang Yu - talking about police work on a Shanghai TV station. He did not catch his name, so he began contacting TV stations in the hope of finding him.

The search took nearly three years. It wasn't until 2013, when a Hangzhou TV show doing a followup on Xia's story identified Jiang as one of the 7,000 police officers assigned to Shanghai's Pudong New Area.

"Xia believed that if he could find me, he might be able to continue his white lie to his wife," Jiang said after learning of the couple's situation. "I didn't know them at all, but their story stimulated the strength and courage in my heart to get to know them.

"His love and persistence was so touching that I saw no reason not to play my part," he added. "It was an incredible moment in my life when I decided to play the role of their deceased son."

Jiang, who is married with two children, said he was nervous before meeting Xia and Liang Qiaoying, who live in a small town in Lyuliang, Shanxi province, more than 1,500 kilometers from Shanghai.

"Though I look like Liang Yu, I don't speak Shanxi dialect," he said.

But his concerns disappeared shortly before the TV show when Xia burst into tears upon seeing him offstage and hugged him. "I was so touched by Xia's emotion, and I was sure then I was the right person to help the family," the police officer said.

Xia and the show's producers arranged everything to convince Liang Qiaoying that Jiang was her son. She was told Jiang could not talk much because his work was of national importance and confidential, which solved the dialect problem.

"The first thing that comes to mind about that moment was calling her mother," Jiang said about the initial meeting. "Now, everything is going well and we're a family. My parents, wife and colleagues are also supportive."

Jiang's work as a police officer means he cannot visit Shanxi often, but he frequently talks to Xia's family by phone or through video calls.

"I send warm clothing every winter, and during holidays, such as Spring Festival and MidAutumn Festival, I send food and other necessities," the police officer said.

In May 2016, Jiang showed the couple around Shanghai on their first visit to the city. They went to the Shanghai Expo, the China Art Museum and the Bund.

Jiang said the absence of a Shanxi accent is no longer a problem, as Liang Qiaoying thinks it must be a result of his Mandarin improving due to years of living in a big city.

After the accident, Xia closed his factory and turned his house into a hostel so that he could be at home to take care of his wife. Their younger son, Xia Hong, is now married and has two daughters.

Xia said his wife has got much better since she first saw Jiang, and she keeps his photo on the bedside table so that she can see him often. "He is, and forever will be, our son," he said.