Former Bishop of Gloucester Peter Ball was jailed last year after he admitted sexually abusing teenagers and young men.
The Diocese of Truro is working to find out what evidence it has that Ball conducted services in the area.
Bishop Ball's brother, Michael, was a former Bishop of Truro in the 1990s.
An independent review is under way into the way the Church of England responded to the case.
Ball, who has been jailed for 32 months for abusing young men in the 1970s and 1980s, was investigated by police in 1993 and given a caution.
Ball promised to resign as Bishop of Gloucester and "immediately leave the country", but instead continued to officiate as a priest in the Church of England until 2010.
The Bishop of Truro, the Right Reverend Tim Thornton said there was no evidence that the Diocese of Truro gave Peter Ball permission to lead services in Cornwall in the 1990s.
The Bishop said: "We have one or two bits of evidence now where it does appear as if Bishop Peter went and did things which Bishop Michael should have been doing.
"It might be that Bishop Peter thought it was clear that he was being Bishop Peter, and on some occasions might have made it very clear at the beginning that he was there in place of his brother, but it might not have been evident to everybody."
He added that it would have been "a limited number of services in a limited number of churches".
Churches are being asked to check records for any evidence that a convicted paedophile bishop may have taken services in the 1990s.