Appearing in public for the first time after he was taken into custody in March last year, Bo, 64, took full advantage of the "open trial" at Jinnan Intermediate Court in eastern China and went back on his earlier testimonies, catching the prosecutors unawares.
Over 100 people were permitted to attended the trial in which five of his relatives 19 journalists were present while the updates on the trial were posted on the court's Twitter- like Chinese microblog Weibo account.
"I had gone against my heart and admitted (accepting bribes from Tang on three occasions) while the Central Disciplinary Commission investigated me," Bo was quoted as saying by the Hong Kong based South China Morning Post.
Looking sullen and rundown, Bo who came to the court wearing an open necked white shirt and tucked between two policemen.
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"I had no knowledge of these details back then, my brain was blank," he said responding to the presiding judge's query if he had accepted the money.
She is also not in the right frame of mind as she is imprisoned serving a suspended death sentence, he said, citing Gu's conviction in the 2011 murder of British businessman Neil Heywood.
Gu had no need to take their shared funds, because she had her own money, which by far exceeded the sums she claimed to have taken from him, he said.
He dismissed Gu's testimony, as read by the prosecutor, calling it "very comical, laughable", state-run CCTV said.