BEIJING—Steven Cao, the CEO of Edelman China's holding company, has been absent from work for more than a week as he cooperates with an official investigation into detained CCTV anchor Rui Chenggang.

Cao's absence comes after it emerged that Rui held a shareholding in Edelman subsidiary Pegasus until 2010. Authorities visited Edelman's Beijing offices on 24 July, said Alan VanderMolen, global vice-chairman of Edelman holding group DJE.

VanderMolen said that it is the firm's "understanding" that Cao is "cooperating fully" with Chinese authorities on the investigation. In the interim, Edelman's 300-person China operation is being overseen by the firm's management team. 

In a statement released last week, Pegasus confirmed that authorities had asked the firm to "assist with an investigation."

Earlier, Pegasus also confirmed that the firm was engaged by corporate sponsors involved in underwriting CCTV's presence at the World Economic Forum in Davos in 2009 and 2010. Rui is also a regular on Edelman CEO Richard Edelman's Trust Barometer panel at the annual event.

"We would have preferred Rui’s shareholding to divest earlier than it did," VanderMolen told the Holmes Report last week. "We weren’t privy to the discussions between the original shareholders. It certainly did not move at the speed with which we understood it would and we desired." 

Edelman has since begun an internal investigation into its relationship with Rui. The firm recently restructured its China operation, merging the bulk of Pegasus with its flagship agency.  

Pegasus, founded by Cao and Rui, was acquired by Edelman in 2007.

Little remains known about why exactly why Rui was detained. The smart money, given the anti-corruption drive launched by President Xi Jinping last year, is that the CCTV anchor has become embroiled in the case built against his former boss, CCTV’s financial news channel director Guo Zhenxi, who was arrested in June.