Denver International Airport manager Kim Day has put DIA operations chief John Kinney on paid "investigatory leave," officials confirmed.It was the second time in less than a year that Day has placed a department head on investigatory leave.DIA officials won't discuss what motivated the suspension. "Denver International Airport does not comment on personnel actions and we can only confirm that John Kinney, Deputy Manager of Aviation for Operations/Public Safety, has been placed on investigatory leave," DIA spokeswoman Jenny Schiavone said in an e-mail Wednesday. "Under the City and County of Denver's Career Service Authority rules, John will have an opportunity to respond to any issue that led to him being placed on leave," Schiavone added. City sources told 7NEWS Reporter Jaclyn Allen that Kinney was placed on leave after employee complaints. Kinney and the airport manager are friends, the sources said, but the complaints must be investigated.Denver Career Service Authority rules allow placing someone on investigatory leave up to 45 days so authorities can investigate possible rule violations, failure to meet standards of performance or if it's determined to be "in the best interest of the city."7NEWS reached Kinney at his home Wednesday, but he declined comment and referred questions to the airport spokeswoman. In October 2009, Day placed DIA chief financial officer Stan Koniz on a similar leave. At that time, Koniz said Day had cited "insubordination" and "lack of collaboration" as reasons for her action after Koniz said he raised concerns about potentially excessive cost of the proposed $1.3 billion South Terminal expansion plan being promoted by Day, according to the Denver Post. Koniz continues to work in the airport financial department in a lesser position. City sources told 7NEWS that the two cases are not related.