The founder of Sunflower Farmers Market resigned as chairman and CEO of the grocery chain Saturday , two days after he was arrested in Phoenix, accused of soliciting sex with an underage girl.Michael Gilliland, 52, was arrested at a Phoenix hotel midday Thursday and booked on suspicion of felony child prostitution, Phoenix police Sgt. Steve Martos said. He was released Friday morning after posting $12,000 bond.Gilliland started the Sunflower chain in 2002 after co-founding Wild Oats Markets in 1987 and growing it from one Boulder store to a billion-dollar publicly traded enterprise with 115 stores in the U.S. and Canada.A statement issued by the Boulder-based Sunflower chain Saturday said Gilliland "has informed the company that he believes he is not guilty of the charges brought against him, and that he expects to be exonerated.""Sunflower appreciates the respect that Mr. Gilliland has shown for the company by his action, so that his personal affairs will not affect the company," said Chris S. Sherrell, who was appointed acting chief executive officer Saturday by the company's board of directors, according to the statement.Sherrell will continue his roles as president and chief operating officer of Sunflower, a discount natural foods chain with 32 stores in Colorado and five other Western states.Police said Gilliland was arrested after he "Solicited sex online with a female who had identified herself as being a minor."Police would not confirm that Gilliland's arrest was part of a sting operation where an officer posed as an underage girl online. Martos said investigators did not want to publicize police tactics in child prostitution cases and would only call it an "ongoing investigation."Yet, Martos said that Gilliland was one of eight men arrested during a week-long child-prostitution operation."The suspect arranged a meeting with this underage female and drove to this location to meet her for sex," a police news release said. "The suspect agreed to pay the underage female for sexual intercourse."Gilliland had money on him when he arrived at the hotel, where he was arrested by detectives, Martos said."He did advise us who he was and who he worked for," Martos said. Gilliland, who has long lived in the Boulder area, bought a $2.2 million home last fall in the upscale Phoenix suburb, Paradise Valley, according to AZCentral.com.