A University of Hong Kong professor on trial for murder has denied arguing with his wife over her deposit of his HK$4 million (US$515,000) cheque the night he killed her two years ago.

Cheung Kie-chung, 56, also denied knowledge of the deposit but later conceded he was aware that a cheque – in a sum unknown to him – had been deposited into a new Citibank account his wife Tina Chan Wai-man, 53, opened on August 16, 2018.

The High Court previously heard that Chan visited two banks the day she was last seen alive and deposited a HK$4 million cheque Cheung had given her into her new Citibank account, but that it could not be cashed due to insufficient funds in his account.

The associate professor had testified to writing the cheque upon Chan’s request on August 15, following similar demands earlier that year: for HK$6 million in February and another HK$6.7 million in response to an IOU showing he owed her that sum on May 31.

But he said the two earlier cheques were not cashed and he believed she was only holding them as proof he owed her money.

Cheung had also confirmed that he had about HK$120,000 (US$15,000) in his bank accounts as of August 16, plus an overdraft facility, some loans and five properties – jointly owned with his wife – on mortgage.

On the fourth day of his testimony, prosecutors suggested that Chan had called Cheung outside the bank at about 5pm on August 16 to tell him she had opened a new account and deposited HK$4 million.

Cheung disagreed with the prosecutors’ account, but later recalled that a bank employee had spoken to him on the phone and mentioned that Chan had deposited a cheque into a newly opened account.

He also denied suggestions he had told his daughter Nancy that the HK$4 million was a joint investment with Chan, or that he was planning to transfer the funds if they had not argued in the early hours of August 17.

“I did not have this amount of money,” he said on Tuesday.

The professor said he only became aware that his HK$4 million cheque had bounced when a bank charge of HK$150 (US$19) was deducted from his account.

When asked by the leading prosecutor whether he knew the bank could call in loans in the worst-case scenario of receiving a bounced cheque, Cheung said he was not aware of the possible consequence.

But he said he could sell the properties to repay any possible loans and agreed with the prosecutor that he had led “a frugal and economical life”.

Senior assistant director of public prosecutions Jonathan Man Tak-ho pressed on: “I put it to you that in fact before the killing you had an argument with your wife about her depositing the cheque into her account.”

Cheung replied: “It didn’t happen.”

The professor has admitted killing his wife on August 17, 2018 and covering it up before his arrest on August 28.

But he pleaded not guilty to murder, presenting the defence of provocation and diminished responsibility, based on his depression, which his lawyers said had substantially impaired his mental culpability for the killing.

His testimony continues before Madam Justice Anthea Pang Po-kam on Wednesday.