Kurt Willi Jarant, 91, was in a wheelchair and wearing sunglasses as his widow and her daughter attempted to check him in at Liverpool John Lennon Airport, northwest England, on Saturday.
Airport staff helped the elderly man, who suffered from Alzheimer's, out of a taxi into the wheelchair when he arrived with the women. All three had been due to travel on the flight.
But officials became suspicious and took his pulse, discovering he had passed away.
Police said they detained his widow Gitta Jarant, and her daughter, Anke Anusic, at the airport on suspicion of having failed to give notification of death. The women have been released on bail.
The pair, who live in Oldham, northwest England, denied Tuesday he was dead when they brought him from their home by taxi to take the flight to Germany.
A police doctor said he had been dead for more than 24 hours, according to Anusic, but she fiercely denied this.
"They would think that for 24 hours we would carry a dead person?" the 41-year-old told the BBC. "This is ridiculous. He was moving, he was breathing."
The pair said they thought that with his eyes closed the elderly man was asleep.
"He was alive. He was pale but he wasn't dead," Anusic added.
Gitta Jarant, 66, told the broadcaster her husband, whom she called Willi, was "the best man in the world."
"Everyone loved him and everyone was in shock about his death," she said. "I loved my Willi."
Anusic added: "So many people had seen him in the previous 24 hours. We had checked his temperature and checked his well-being. The accusations are wrong. When we were detained at the airport we thought it was normal procedure - we were only arrested after a nine-hour wait," she added.