Murderess Dorothea Waddingham made headlines in 1936 when she became the only woman to be hanged at Birmingham's Winson Green Prison.
She was found guilty of poisoning an 87-year-old widow and her disabled daughter at a nursing home.
So hairdresser Chris Canner, aged 57, was understandably shocked when research into his family tree showed they were related.
But Mr Canner was so intrigued by the story he embarked on a mission to find her final resting place.
Waddingham, aged 36, was the only woman to hang at Winson Green and was one of only 12 women in England to be executed in the last century.
Mr Canner, from Derby, said: "It was quite strange to discover I was related to her, but the more I found out about her case the more interested I became.
"I find it rather sad that I don't know where she came to rest. She is family, after all.
"Although she committed murder, I always feel that as I've delved so far I want to go a little bit further. What I would really like to know is what happened to Dorothea. I would like to find her final resting place."
In 1978 or 1979 her body was exhumed from Winson Green Prison because the grounds were being rebuilt. It was taken from there for either cremation or reburial.
Mr Canner said: "Bodies were offered to the families but in Dorothea's case no one came forward. The prison don't know what happened to her body because her records were destroyed after 20 years.
"Neither the Home Office nor the Prison Service have been able to help. I've tried contacting local burial grounds and crematoriums but no one knows anything about her.
"I believe her final resting place was somewhere in Birmingham."
Waddingham married Willoughby Leech, Mr Canner's first cousin, in Burtonupon-Trent, in 1925. They had three children - Edwin, Alan and Dorothea junior.
After Mr Leech died of throat cancer in 1933, she moved in with an old friend, Ronald Joseph Sullivan, and they had two children, Ronald and Margaret Maureen.
In 1935, Waddingham and Sullivan opened a nursing home in Devon Drive, Nottingham. Her only medical experience was from working as an orderly in the Burtonon-Trent Workhouse, but she still managed to get a licence.
Her first two patients were 87-year-old Louisa Baguley, who was senile and bedridden, and her paralysed daughter Ada Louisa, aged 50.
Waddingham struck a deal with Mrs Baguley, promising to care for both women until they died if she left her everything she owned. Mrs Baguley changed her will, leaving £1,600 to Waddingham.
When she died six days later no one was suspicious because of her age. But then Ada died just three months later.
Waddingham forged a letter from Ada saying she wanted to be cremated and did not want her relatives informed of her death. She sent it to the medical officer who became suspicious. He found three grains of morphine during a postmortem examination.
The body of Mrs Baguley was exhumed and tests revealed she, too, had been given a fatal dose of morphine.
Waddingham and Sullivan were both charged with murder. The trial lasted just four days but Sullivan was cleared because of a lack of evidence.
Waddingham was found guilty on February 27 1936 and hanged 39 days later.