The ongoing legal battle between former President Donald Trump and the Manhattan District Attorney's office has taken a new turn with the testimony of Bob Costello, a former attorney for Trump's longtime fixer Michael Cohen. Costello appeared before a grand jury on Friday and reportedly told prosecutors that Cohen is a serial liar who cannot be trusted. He also claimed that Cohen had lied to him about the nature of his work for Trump, and that he had been misled about the extent of Cohen's involvement in the hush money payments made to adult film actress Stormy Daniels. The testimony of Costello, who has known Cohen for decades and represented him in the past, is seen as a significant blow to the defense of Trump and his associates. It suggests that Cohen's credibility as a witness is being called into question, and that his testimony may not be enough to secure a conviction against Trump. The case against Trump centers on allegations that he and his company, the Trump Organization, engaged in financial fraud and tax evasion. Prosecutors are also investigating whether the company improperly valued its assets in order to obtain loans and tax benefits. Trump has denied any wrongdoing and has accused the Manhattan DA's office of conducting a politically motivated witch hunt. He has also sought to block the release of his tax returns, which could shed light on his financial dealings. The testimony of Costello is just the latest twist in a long and complex legal battle that has been playing out for years. It remains to be seen how it will impact the case against Trump, but it is clear that the Manhattan DA's office is leaving no stone unturned in its pursuit of justice. As the investigation continues, it is likely that more witnesses will be called to testify, and more evidence will be uncovered. The outcome of the case could have far-reaching implications for Trump and his associates, and for the future of American politics.