I'm unsure exactly which claims you want validated, but BBC seems to have the relevant facts:
>Andriesz's family said he had taken his own life on 23 September, and that there was no suggestion of foul play. ...
>Weeks before his death, Andriesz told a public event led by MPs, whistleblowers and campaigners calling for fairer regulation that he felt "thoroughly let down" and had been put through "absolute hell" by the [Financial Conduct Authority], to whom he had sent evidence of what he regarded as whistleblower retaliation by [his former employer previously run by Lutnick] BGC and its lawyers.
>The FCA had previously told Andriesz there was "insufficient evidence" to conclude there had been retaliation, a conclusion he believed made it harder to win a claim against BGC at tribunal.