Barrister and part-time judge Constance Briscoe has been found guilty of lying to police probing ex-cabinet minister Chris Huhne's speeding points case.
The 56-year-old was accused of lying in the inquiry into Huhne, who got his wife to take speeding points for him.
Briscoe had denied at the Old Bailey three counts of intending to pervert the course of justice.
She will be sentenced on Friday. Trial judge Mr Justice Baker said a custodial sentence was "almost inevitable".
Clive Coleman reports on Constance Briscoe's fall
Now, a BBC investigation has learned Briscoe is facing a further criminal investigation into claims she fraudulently obtained medical documents to support her defence in a libel case brought against her by her own mother.
Carmen Briscoe-Mitchell unsuccessfully attempted to sue over claims of childhood cruelty made in Briscoe's 2006 memoir, Ugly.
Briscoe was found guilty on three counts.
The first charge alleged that, between 16 May 2011 and 6 October 2012, Briscoe provided police with two inaccurate statements, and the second that on October 6 2012 she produced an altered copy of a statement but claimed it was the correct version.
A third charge alleged that between 5 October 2012 and 8 October last year she deliberately got a document expert to view the wrong version of her witness statement.
Briscoe stood trial at London's Southwark Crown Court in January but a jury failed to reach verdicts on any of the counts.
A retrial was ordered which has been heard at the Old Bailey.
Jurors were told that Briscoe helped Huhne's wife Vicky Pryce, who was a friend and also her neighbour, to reveal information about Huhne's points-swapping to newspapers after the couple split in 2010.
The scandal led to Huhne's resignation and subsequent prosecution.
He pleaded guilty in February last year, while Pryce was convicted after a trial in which she had denied perverting the course of justice.
Huhne and Pryce, who are now divorced, were both jailed last year for perverting the course of justice and have since been released from prison.
When the allegations emerged in 2011, Briscoe made a witness statement to police on 31 May that year claiming Pryce confided in her in 2003 after she found out that Huhne had asked her to take his speeding points, portraying herself as an "independent and objective" witness.
In a second statement on 16 August 2012 she denied having any contact with journalists or newspapers about the story but emails obtained by court order ahead of the Huhne-Pryce trial showed that Briscoe had spoken to journalists.
Once her involvement was revealed, Briscoe was dropped as a witness in Huhne and Pryce's trial and she was arrested in October 2012.