Ramadan Guney was the owner of Brookwood Cemetery in Woking
A cemetery boss accused of hiring a hitman to kill his late father's lover told an Old Bailey jury that he had spotted a "police set-up".
Erkin Guney, 44, managing director of Brookwood Cemetery in Woking, Surrey, denies soliciting the murder of Diane Holliday in 2008.
The prosecution claims he wanted to stop her claiming his father's fortune.
He told jurors he spotted an undercover officer and played along with the subterfuge to find out the truth.
Mr Guney said: "An undercover policeman turns up in a big blue Jag. It was clear I was being set-up.
"It's a quiet car, it's a big car. I have past experience of installing covert surveillance equipment.
"I was quite experienced, familiar with the kind of cars police use. I was licensed by the Home Office."
He said he had previously owned a firm which fitted monitoring and communication equipment to police vans and security vehicles.
Mr Guney added: "I knew it would end up here but I wanted to get at the truth. I wanted to know who had issued the warrant. Someone was setting me up. I wanted to know who."
The prosecution claims he hired a hitman, who turned out to be an undercover police officer, to kill his father's mistress.
The court was told earlier that Surrey Police staged an accident near Miss Holliday's home, to persuade Mr Guney that she had been run over, but he did not turn up to pay the 'hitman' the promised £10,000.
He was later arrested at his home where about £23,000 in cash was also found, jurors were told.
Mrs Holliday, 47, had been living with Mr Guney's late father, Ramadan, 76.
She has denied defence claims that she was a "gold digger" and had tried to blackmail Harrods boss Mohammed al-Fayed, after his son Dodi died in the Paris car crash with Diana, Princess of Wales in 1997.
The trial continues.