Since moving to Washington, Scott Pruitt, the head of the Environmental Protection Agency, has attracted the attention of federal investigators because of his unusual association with lobbyists, including his rental of a condominium last year owned by the wife of a lobbyist with business before the EPA.

As a state senator in Oklahoma 15 years ago, Pruitt went even further: He bought a home in the state capital with a registered lobbyist who was pushing for changes to the state’s workers’ compensation rules — changes that Pruitt championed in the Legislature.

And as with the condominium rental in Washington, Pruitt never publicly disclosed his financial relationship with the lobbyist, who, like Pruitt, lived in the home when in Oklahoma City on business.

The lobbyist, Justin Whitefield, represented as many as a dozen organizations, including some that sought business-friendly changes to Oklahoma’s workers’ compensation rules.

Pruitt pressed for the changes, often bemoaning the high costs to businesses of the existing rules and suggesting that lawyers were enriching themselves off the system. Another of Pruitt’s business partners, Robert Funk, who owned a local baseball team with him, ran a large staffing company that would benefit from relaxed rules; he also joined Pruitt in pushing for the changes.

The home in Oklahoma City was registered to a shell company owned by Pruitt, Whitefield and four other associates. The New York Times reported last month that the house was bought at a steep discount from a lobbyist, Marsha Lindsey, who worked for a telecommunications company with business before the Oklahoma Legislature.

Whitefield died in a plane crash in 2006. A relative confirmed to the Times that he had shared the home with Pruitt.

Pruitt is now facing 11 federal investigations into matters including his condominium rental in Washington and his spending on travel and security at the EPA.

Pruitt, Whitefield and the other investors in the shell company bought the Oklahoma City home in December 2003 for $375,000, a discount of about $100,000 from what Lindsey had paid a year earlier. Her employer, the telecom giant SBC Oklahoma, now AT&T and formerly known as Southwestern Bell, used a relocation firm to handle the sale and picked up the shortfall under her retirement package. AT&T said the home had been appraised twice, for an average value of $390,000, before the sale.