Kweku Adoboli, the UBS trader accused of running up losses of £1.5bn, broke down and cried minutes after taking the witness stand in his trial at Southwark crown court on Friday.Adoboli, 32, choked up when he was asked about his father, his early life in Ghana and his former boss Mike Foster, who was in charge of the exchange traded funds (ETFs) desk when Adoboli joined as a junior trader in 2006."He wanted to make sure we could build something we could all be proud of," Adoboli said of Foster, his voice choking with emotion. Tears then welled up in his eyes and he was unable to continue.The judge told Adoboli he should not be embarrassed, and that it was clear he was becoming emotional when talking about people he cared about such as his father or Foster, who has supported him throughout his trial. Foster no longer works for UBS.Adoboli managed to compose himself and went on to begin his defence, saying that he did not believe his behaviour had been fraudulent and it was unfair to suggest that his previous jobs in the UBS back office had given him the knowledge and skills to commit fraud. He denies four counts of false accounting and two of fraud.Answering questions from his defence counsel in a packed courtroom, Adoboli said he had been asked to bring his "ability to understand the interaction of systems" to the ETF desk.He told the court he did not believe his "rare skillset" had made it easier for him to exploit the bank."The reality is systems and processes evolve, number one," Adoboli said."Number two, the reality is every single trader, and salesperson, trade support adviser and settlement person has a duty to understand the system, the tools that we use."So I do not think it is fair to say that my experience in settlement and trade support enabled me to more easily do something that has been characterised as fraud."Those experiences enabled me to do my job to the best of my ability."It is not fraudulent, it is finding a way to do your job."