Francisco Rodriguez Jr failed a drug test in America in December, six months before his fight with Galal Yafai in Birmingham.
Rodriguez, 31, beat Olympic gold medallist Yafai in a points decision in June, with the British boxer suffering his first defeat as a professional.
After the fight, Rodriguez tested positive for banned substance heptaminol and the Mexican is now under investigation by the British Boxing Board of Control (BBBofC) and UK Anti-Doping (Ukad).
The test was conducted on fight night and administered by the Voluntary Anti-Doping Association (Vada), as part of the WBC’s Clean Boxing Program.
But it has now emerged that this is the second time Rodriguez has failed a drug test in six months.
Rodriguez’s win over Josue Jesus Morales on December 15 in San Antonio was declared a no-contest by the Texas Commission after he failed a post-fight drug test.
“Francisco Rodriguez failed his drug test on 15/12/24 and was put on a 90-day suspension and was assessed a $500 administrative penalty,” the Texas Combative Sports Program said.
There is no world governing body in boxing and the Texas Commission are not required to inform other commissions of the decision.
The commission did say Rodriguez’s suspension was recorded on the national data base Boxrec.com as “rules violation” which the British Boxing Board of Control have access to.
Before Rodriguez’s fight with Yafai, BBC Sport reached out to the Texas Commission to ask why his fight with Morales was registered as a ‘no-contest’ but received no reply.