A man accused of the crossbow killing of a retired lecturer lied to police because he did not want to reveal his gay affair, a court has heard.

Sports therapist Terence Whall, 39, told Mold crown court he was near the remote Anglesey home of Gerald Corrigan, 74, on the night of the fatal shooting because he was engaging in sexual activity with friend Barry Williams in a field nearby.

Corrigan was injured as he adjusted his satellite dish in the early hours of the morning of Good Friday on 19 April last year and died in hospital almost a month later.

When police initially asked Whall where he was at the time of the shooting and on the previous night, when he is alleged to have carried out a “reconnaissance”, he said he had been at the home he shared with partner Emma Roberts in Bryngwran, Anglesey. A GPS system from his Land Rover Discovery, which was discovered burnt out in a disused quarry last June, showed he had been in the area.

Cross-examining Whall on Friday, Peter Rouch QC, prosecuting, asked why he had not told police the truth. Whall, who denies murder, said: “What I do with my sexual life is my private business and nothing to do with North Wales police or the Sun newspaper or everyone else. There’s nobody knows the gravity of this situation more than me. I’ve had my name dragged through the papers.”

He added: “I didn’t really want to admit I’d been there with Barry. I didn’t think they had the right to know.”

Williams has denied having a sexual relationship with Whall.

Whall said he had owned a crossbow but sold it to a man who called at his house some time around January, three months before the attack on Corrigan.

He ordered a new crossbow online but it did not arrive until after 19 April, the court heard. But the jury was told he ordered crossbow bolts and broadheads from Amazon in February and March. Asked why he ordered them if he did not own a crossbow, Whall said: “I’ve already said I was planning on getting another crossbow.”

He said on the evening of 17 April he drove to Corrigan’s home near South Stack because he thought the house was empty and he wanted to go to the nearby clifftop to meditate. While there he also looked for somewhere he could go with Williams the following night, he said.

The tai chi instructor said he parked his car on the drive of the house while he walked in the nearby field and later moved it to Porth Dafarch beach, where he walked back to the field and the clifftop. Rouch said: “You were scoping the house out, weren’t you?” Whall replied: “No.”

The court heard in the week leading up to Friday 31 May, Whall placed a tracker on a car used by Richard Wyn Lewis, who the jury has been told is under investigation for offences of fraud in relation to Corrigan and his partner Marie Bailey.

Whall said he placed the tracker on the car because it was owned by a man named Geraint Williams and he believed Lewis was going to steal it and take it to Ireland. He said: “He is a con artist. He preys on the elderly.”

With co-defendant Gavin Jones, 36, of Bryngwran, Anglesey, Whall also denies conspiracy to pervert the course of justice and conspiracy to commit arson in relation to the Land Rover, which Whall claimed was stolen before it was found burnt out.

Jones’s brother Darren Jones, 41, and Martin Roberts, 34, have admitted arson. The trial was adjourned until Monday.