Twelve years ago, Sonny Graham's heart was failing and he was on the verge of death, until he received a call from doctors, saying a donor heart had just become available.

That heart belonged to Terry Cottle, 33, who had committed suicide by shooting himself in the head.

The operation was a success and soon after, Mr Graham, 69, contacted the organ donor agency, saying he wanted to thank Mr Cottle's family.

He began writing to Mr Cottle's widow, Cheryl, 39, and they soon fell in love and were married in 2004, moving to the US state of Georgia.

After the wedding, Mrs Graham said: "It helped me so much. Meeting Sonny made it easier for me, knowing something so good came from something so bad."

In a newspaper article published in 2006, Mr Graham said he felt an instant and unusual attachment when he met his donor's widow.

"I felt like I had known her for years," Mr Graham said. "I couldn't keep my eyes off her. I just stared."

But now, 12 years after the operation, Mrs Graham's life has been rocked by another tragedy.

Mr Graham killed himself with a shotgun, in circumstances similar to those which claimed Mr Cottle's life.

His friends said he had shown no signs of being depressed and were at a loss to explain his sudden death.

According to scientists, there are more than 70 documented cases of transplant patients taking on some of the personality traits of the organ donors.