An army sergeant accused of attempting to murder his wife by tampering with her parachute before a skydive has told a jury that a “random killer” may have been responsible.

Emile Cilliers said it was possible that an “insider” with technical knowledge of parachutes had sabotaged the parachute his wife Victoria used when she fell 1,200 metres (4,000ft) to the ground.

Cilliers insisted from the witness box at Winchester crown court that he had not wished any harm on his wife and did not stand to gain financially from her death.

Asked by his barrister, Elizabeth Marsh QC: “Did you want to harm Victoria?” he replied: “No.” His barrister asked him: “Did you want to kill Victoria?” Again he replied: “No.”

But under cross-examination Cilliers said he did not believe his wife’s fall was an accident, nor did he believe Victoria had tampered with her own parachute rig. He said he did not know of anyone who bore Victoria a grudge and may have wanted to kill her.

Cilliers said: “I’m not trying to point the figure at anyone else; I’m just trying to get to the bottom of it ... All I know is that I didn’t have anything to do with it so someone must have.”

Michael Bowes QC, prosecuting, suggested that if a random stranger had tampered with the hired rig he or she would have had no idea who the victim was going to be and so could have no motive. He put it to Cilliers that: “It’s a motiveless random killer – or you.”

Cilliers, 37, is accused of deliberately removing vital components called slinks from the rig, which led to Victoria, 42, an expert skydiver and instructor, plummeting to the ground during a jump in Wiltshire. She survived but sustained severe injuries.

The jury heard that a week before the incident at the Army Parachute Association camp at Netheravon, Salisbury Plain, Cilliers allegedly tried to kill his wife by interfering with a gas pipe at their home, hoping to cause an explosion when she lit the stove.

Cilliers, who denies two charges of attempted murder, is alleged to have had debts of £22,000 and the prosecution claims he believed he would receive a £120,000 insurance payout if his wife died.

The jury heard that at the time of the incident over the Easter weekend in 2015 Cilliers was having an affair with an Austrian skydiver called Stefanie Goller he had met four months before via the dating app Tinder while on an army skiing expedition.

Asked why he had been using the app, he said he was “far away from home” and added: “I needed some female company, someone to talk to.”

At the time, the court heard, Victoria was pregnant with their second child and messaged him that she loved and missed him. She said she was feeling “very low”, had “had enough of life” and had failed him as a wife.

Cilliers told the jury: “I know she was very emotional … I don’t know if she was trying to get more attention from me.”

He continued: “I was having troubles thinking about what I really wanted. I didn’t feel happy in my marriage and Stefanie was something new.”

Cilliers lied to Goller that the child his wife was expecting was not his. In the witness box he called this lie “cowardly”.

Despite his dire finances he travelled around Europe to meet up with Goller and had booked a holiday in central America with her.

Cilliers was also asked about a text message Victoria sent him after the gas pipe incident in which she asked him if he was trying to “bump her off”. He told the court: “She had a funny sense of humour.”

The trial continues.