ZURICH (Reuters) - Credit Suisse CSGN.S aims to wrap up this week an internal investigation into a confrontation between its former wealth management chief Iqbal Khan and private detectives that he claims were shadowing him, a source close to the situation said.

FILE PHOTO: Iqbal Khan, CEO International Wealth Management of Swiss bank Credit Suisse, speaks during "The Wealth Management Industry - Into the next decade" at the Reuters Global Wealth Management Summit, Park Hyatt hotel, Zurich Switzerland, June 13, 2016. REUTERS/Arnd Wiegmann

The confrontation in Zurich last week triggered a criminal investigation by Swiss prosecutors and raised questions about who ordered a detective bureau to trail star banker Khan, who left Credit Suisse in July and will co-head private banking at arch rival UBS UBSG.S from next month.

A number of sources familiar with the matter have told Reuters that Credit Suisse hired security firm Investigo to tail Khan to try to ensure he did not poach any colleagues before joining UBS.

Credit Suisse, Switzerland’s second-biggest bank, has declined to comment publicly on either the confrontation or whether it hired detectives to tail Kahn.

The confrontation between Kahn and the private detectives has been the talk of Switzerland’s banking community for days after it was widely reported in local media.

Credit Suisse Chairman Urs Rohner and Chief Executive Tidjane Thiam told staff in an internal memo this week they would get to the bottom of the matter, which they said had prompted “significant inaccuracies” in sensational media reporting.

Sources had pointed to a serious fallout between CEO Thiam and rising wealth management star Khan, who shared side-by-side villas in Zurich’s Herrliberg suburb, prior to Khan’s departure in July.

A spokesman for Khan, 43, has denied as “absurd” Credit Suisse suspicions that he might be trying to poach former colleagues away to join his new employer.

Contradictory versions of the confrontation have emerged.

Khan filed a criminal complaint alleging threats and coercion after the confrontation on Sept. 17, during which Swiss media reported that Investigo agency detectives sought to take Khan’s mobile phone after he tried to take a photo of their car.

But an Investigo memo seen by Reuters said a single detective had taken only defensive action when Khan tried to photograph him with his mobile phone.

An Investigo representative has said he could not comment on the memo or any details of the incident, but it was very unlikely that one of the firm’s detectives would try to pull the phone from the hands of someone being tailed.

Three employees of the security firm were briefly detained by authorities over the incident, Investigo’s representative has said.

Credit Suisse hired an external law firm to conduct the inquiry, according to a source.

Khan is due to begin his new job at UBS on Oct. 1.