Pinsent Masons is acting for Manchester City on the Premier League club's high-profile investigation into its links to convicted child sex offender Barry Bennell.

Manchester-based commercial litigation partner Julian Diaz-Rainey is heading the firm's team tasked with establishing the nature of the former football coach's relationship with the club.

Bennell was found guilty of 43 charges of historical child sexual abuse last week, and will be sentenced today (19 February).

According to the Daily Mail, the investigation has already taken up 4,000 hours and cost more than £1m, with the Pinsents team interviewing approximately 120 people connected to Manchester City, during a period of 14 months. The firm's team will report its findings to Jane Mulcahy QC of Blackstone Chambers.

Diaz-Rainey previously took a role on the Shipman Inquiry into the actions of GP serial killer Harold Shipman, while he represented soldiers in the Baha Mousa Inquiry into the death of an Iraqi man while held in British Army custody. He was also involved in the Al-Sweady Inquiry, which looked into the mistreatment of prisoners by the British Army following the Battle of Danny Boy in southern Iraq.

He has advised a number of other top football clubs on issues such as contractual disputes, disciplinary proceedings and sponsorship agreements. He joined Pinsents in 2012 after two years at Hill Dickinson, before which he was at now-defunct firm Halliwells.

Other law firms to have taken related roles include Slater and Gordon, for which principal lawyer Kim Harrison is acting for a number of victims, one of who was involved with Manchester City. She is a member of the firm's abuse team and also acted for victims during the Catholic and Anglican Church abuse scandals.

Bolt Burdon Kemp associate solicitor Dino Nocivelli is also advising a number of Bennell's victims. Nocivelli, who acts for a number of child abuse survivors within football, said: "The sentencing today is only about Bennell and it does not look towards the football clubs, who have not provided an acknowledgment of what happened and recognised their involvement. That is what survivors are looking for; an admission of responsibility and an apology. Today will provide an element of closure, but it is not the full picture – the clubs have not accepted their role."

Bennell, who had worked as a youth football coach and scout since the 1970s, had close ties to both Manchester City and Crewe Alexandra Football Club. He was first convicted in 1994 for sexually abusing a 13-year-old boy during a football tour to Florida and was sentenced to four years in a US prison.

He was convicted again in 1998, after pleading guilty to 23 offences committed in the 1970s, 1980s and 1990s. In 2015, he was jailed for two years, pleading guilty to two counts of indecent assault and two counts of enticing a boy under the age of 14 to commit an act of gross indecency.

Pinsents declined to comment. Slater and Gordon and Manchester City were approached for comment.