Tar balls and puddles of oil are reported on Alabama’s Dauphin Island.

(CNN) — Oil from BP’s massive Gulf of Mexico crude spill reached the shores of Mississippi on Tuesday, Gov. Haley Barbour’s office reported. Residents and researchers reported oil in Alabama.

In Mississippi, a long, narrow strand of oil came ashore on Petit Bois Island, Barbour’s office said. The strand of oil was about 2 miles long but only 3 feet wide, said Laura Hipp, a spokeswoman for Barbour’s office. Cleanup crews were on the scene Tuesday evening, she said.

Petit Bois Island is off Pascagoula, Mississippi. It’s about five miles west of Dauphin Island, Alabama, where oil was also washing ashore Tuesday afternoon. But Hipp said most of the oil remained more than 35 miles off Horn Island, the largest of Mississippi’s barrier islands.

The National Oceanographic and Atmospheric Administration had warned earlier this week that the spreading slick from an undersea BP oil well was heading toward the Alabama and Mississippi coasts. Tar balls associated with the Gulf spill had hit Dauphin Island, about 35 miles south of Mobile, in early May, but residents said that Tuesday was the first time they had seen oil hitting the beach. Nevertheless, people were still on the beaches and swimming in the blue-green waters.

BP began its latest attempt to curtail the flow of oil from an underwater well in the Gulf of Mexico on Tuesday, using robot submarines to cut into a damaged pipe a mile down.

The operation carries the risk that the flow of crude from the ruptured well, already the largest oil spill in U.S. history, will increase — but if successful, the company says it will be able to catch most of that oil with a cap it plans to place over the severed lower marine riser pipe.

“Even with an increased flow rate, this cap will be able to handle this,” BP Managing Director Bob Dudley told CNN’s “American Morning.”

Meanwhile, the Obama administration distanced itself from BP by announcing it would no longer hold joint news conferences with the company; and Attorney General Eric Holder, after meeting with Gulf-Coast-state attorneys general, told reporters the Justice Department has launched a criminal investigation into the oil spill.

The engineering involved in the latest work on the damaged well has never been attempted at a depth of 5,000 feet. But Dudley said Tuesday the latest attempt is “more straightforward” than previous, unsuccessful efforts.

A mechanical claw began squeezing the heavy riser pipe late Tuesday morning, the first step in a series of planned cuts. After that, a diamond-cut saw was being brought in to make a “clean cut,” preparing the way for the custom-made cap to be fitted over the lower marine riser package.

Oil has been gushing from the undersea well since April 20 when the Deepwater Horizon oil rig exploded and later sank. Government estimates are that up to 19,000 barrels (798,000 gallons) of oil a day are flowing into the Gulf of Mexico. Dudley said that could increase by up to 20 percent — nearly 160,000 gallons — when the pipe is cut, but he said the company has learned lessons from its earlier attempts that it is applying to the new process.

Warm water and methanol will be pumped into the cap to limit the growth of gas hydrate crystals that thwarted an earlier attempt to cap the spill, he said. And a second line is planned to draw more oil off the well’s blowout preventer, a critical piece of safety equipment that has so far failed to shut down the well, using equipment involved in last week’s failed “top kill” operation.

BP’s handling of the spill and its statements regarding the status of operations have been sharply criticized by some in recent weeks. The Obama administration announced Tuesday that it would no longer hold joint news briefings with the company and that Coast Guard Adm. Thad Allen, its point man on the spill, will now become the face of the government’s response effort.

Allen told reporters in New Orleans, Louisiana, that his job is to speak “very frankly with the American public.”

“I think we need to be communicating with the American people through my voice as the national incident commander,” he said.

Rear Adm. Mary Landry, who has been the Coast Guard’s on-scene coordinator for five weeks, will be returning to her duties as chief of the service’s New Orleans district office. Coast Guard Commandant Robert Papp said the plan always has been for Landry to resume that role in preparation for the Atlantic hurricane season, which began Tuesday.

Allen praised Landry’s work leading “an anomalous and unprecedented response” to the spill, but said Landry now needs to focus “on the larger array of threats” to her district, which includes the U.S. Southeast and Midwest.

The oil spill has spread across much of the northern Gulf of Mexico, washing ashore in the environmentally sensitive marshes along the Louisiana coast that serve as the cradle of the region’s fishing industry. Plaquemines Parish President Billy Nungesser said crude has fouled 24 miles and about 2,965 acres of the state’s coastline, and the start of hurricane season raised new worries that a storm could drive more oil ashore.

“We don’t want to scare anybody, but we need to be realistic about it,” Nungesser said. “If a storm does top out levees, it will probably bring oil with it.” He said residents who evacuate ahead of a hurricane might return “not to a flooded home, but to a home that is completely contaminated with this oil.”

“I don’t know how to soft-pedal that,” he said.

Tuesday also marked the start of the recreational fishing season for red snapper, a big draw for sport anglers in the region. But the season opened with a new blow to the region’s fisheries industry as the National Oceanographic and Atmospheric Administration extended its restrictions on fishing to nearly a third of the Gulf.

The latest closures extend southward to a point about 240 miles west of the tip of Florida and eastward to federal waters off the Alabama-Florida state line.

Holder met with state attorneys general and federal prosecutors from Louisiana, Alabama and Mississippi on Tuesday, emerging to tell reporters that the Justice Department was looking at possible criminal violations in connection with the spill as well as working to make sure BP paid the full cost of the cleanup.

Justice Department launches investigation

“If we find evidence of illegal behavior, we will be forceful in our response,” he said. “We have already instructed all relevant parties to preserve any documents that may shed light on the facts surrounding this disaster.”

A group of senators asked Holder to look into whether BP had leveled with federal officials in the exploration plan it filed with the government for the site, expressing concerns about BP’s “truthfulness and accuracy.” But in a reply to that letter last week, a Justice Department official did not say whether a criminal investigation had begun.

In a statement issued in response to Holder’s announcement, BP said it would cooperate with any inquiry, “just as we are doing in response to the other inquires that are already ongoing.”

BP, as the well’s owner, is responsible for the costs of the cleanup under federal law. The company said Tuesday that the tab for its response to date was $990 million. BP, rig owner Transocean Ltd. and oilfield services company Halliburton have blamed each other for the disaster, which left 11 workers dead.

BP stock has taken a beating on Wall Street since the spill and plunged 15 percent on Tuesday after the failure of the “top kill” plan, which pumped heavy drilling fluid into the damaged well in hopes of holding back the flow. The company’s stock value is down more than a third since the April 20 explosion on the rig.

The spill may not be completely under control until August, when BP expects to complete relief wells that will take the pressure off the one now spewing into the Gulf. If attempts to capture more of the leaking oil fail, White House energy adviser Carol Browner said, “we would be in a situation where it is conceivable that there would be oil leaking at a rate of something on the order of 12 to 20,000 barrels a day until the relief wells are dug.”

The Obama administration has always hoped for the best, “but we are preparing for the worst,” she said.