LITTLE ROCK — Attorney General Dustin McDaniel on Tuesday asked Exxon Mobile Corp. to preserve all documents and other information related to an oil spill and cleanup efforts in Mayflower.

Exxon Mobil’s Pegasus pipeline ruptured Friday, leaking crude oil onto streets and yards in a residential neighborhood. Nearly two dozen homes in the area were evacuated. Crews had recovered nearly 12,000 barrels of oil and water by Monday.

In a letter to Exxon Mobil officials Tuesday, McDaniel said his office would open an investigation into the cause and the impact of the pipeline rupture, which threatened nearby Lake Conway. The attorney general said the spill left significant damage to the environment and to property in the surrounding area.

"This incident has damaged private property and Arkansas’ natural resources. Homeowners have been forced from their homes as a result of this spill," McDaniel said. "Requesting that Exxon secure these documents and data is the first step in determining what happened and preserving evidence for any future litigation."

McDaniel said he expects Exxon Mobil to comply with his request.

His letter asks the oil company to require any affected employees and affiliated organizations to preserve all "documents, data compilations (including electronically recorded and stored data), tangible objects or other information" relevant to the pipeline rupture, spill and cleanup.

He requested that Exxon Mobil take all necessary measures to prevent destruction or modification of those records.

Meanwhile Tuesday, crews began replacing soil in affected neighborhoods and Exxon Mobile said a plan was being developed for the phased return of residents to 22 homes in the area. The timing of residents’ return home will be determined by the state Health Department, the company said.

Exxon Mobile and the federal Environmental Protection Agency continued monitoring air quality in the affected areas and were providing data to the Health Department. Current air quality readings were below levels likely to cause health effects, the company said, but members of cleanup crews were using monitors and breathing equipment when necessary.

U.S. Environmental Services has begun a wildlife rehabilitation operation on-site and is working with Animal Response Services on a treatment program. Fourteen oiled ducks, two turtles, and one muskrat have been recovered for treatment. Two ducks have been found dead. Officials urged residents to avoid wildlife for safety reasons.

Exxon Mobil said it had established a claims hotline (1-800-876-9291) for residents affected by the spill to register a claim and get more information. About 90 claims had been made by Tuesday, the company said.