A BP executive who led the company's efforts to halt its massive 2010 oil spill in the Gulf of Mexico testified Tuesday that his decisions were guided by the principle that they shouldn't do anything that could make the crisis even worse.

James Dupree, BP's first witness for the second phase of a trial over the deadly disaster, said his teams worked simultaneously on several strategies for killing the well that blew out in April 2010.

Dupree said the company decided in mid-May that it wasn't ready to employ the capping strategy. He also said he was concerned that it could jeopardize other efforts to seal the well.

"We were very intent not to make the situation worse," said Dupree, who was promoted to BP's regional president for the Gulf of Mexico after the spill was stopped. Dupree is scheduled to resume his testimony Wednesday.

BP's trial adversaries have argued that the company could have stopped the spill much earlier than July 15 if it had used the capping strategy.

Earlier Tuesday, an employee of the company that owned the doomed Deepwater Horizon drilling rig testified that he was surprised when BP scrapped the capping strategy his team had devised and never heard an explanation for the decision.

"We were so close. We had come a long way," said Robert Turlak, Transocean's manager of subsea engineering and well control systems.

During the first few weeks after the spill, engineers focused on two methods for stopping the flow of oil: Capping the well was one option. The other, called "top kill," involved pumping drilling mud and other material into the Deepwater Horizon rig's blowout preventer.

BP ultimately used a capping stack to stop the spill July 15 after several other methods failed.

Turlak's team was working on a strategy that was called "BOP-on-BOP" because it lowered a second blowout preventer on top of the rig's failed one. He called it the "obvious solution" and said it was ready for installation in early June.

But BP concluded it wasn't a viable option because it could have made the situation worse and hampered other strategies if it failed. BP said the capping stack that later sealed the well was specifically designed to land on the well system above the blowout preventer.

BP employed the "top kill" method in May 2010, but it didn't stop the flow of oil. The company says its adversaries have ignored evidence that the "BOP-on-BOP" option wasn't approved or ready for safe installation before "top kill."

The trial's second phase opened Monday with claims that BP ignored decades of warnings about the risks of a deep-water blowout and withheld crucial information about the size of the spill. Plaintiffs' lawyers claim BP knew the "top kill" strategy was doomed based on higher flow rate estimates that the company didn't share with federal officials at the time.

U.S. District Judge Carl Barbier, who is presiding over the trial without a jury, also heard videotaped testimony Tuesday by a manager employed by cement contractor Halliburton. Richard Vargo, who assisted on the top kill attempts, said he didn't learn until later that BP didn't believe the procedure would work given the high flow rates.

"I'm pretty angry," Vargo said, choking back tears.

The trial's first phase, which ended in April, focused on the complex chain of mistakes and failures that caused the blowout.

The second phase is divided into two segments: The first centers on BP's efforts to cap the well. The second is designed to help Barbier determine how much oil spilled into the Gulf.

The government's estimate is 70 million gallons more than what BP says spilled. Establishing how much oil leaked into the Gulf will help figure out the penalties the oil company must pay. Billions of dollars are at stake.

Eleven workers died in the explosion on the rig that was triggered by the blowout.

University of California-Berkeley engineering professor Robert Bea, an expert witness for plaintiffs' attorneys, testified that BP didn't spend any money before the Deepwater Horizon disaster to develop technology for controlling a deep-water blowout. At the time of the Macondo blowout, the company's oil spill response plan simply called for assembling a team of experts to assess the situation while drilling a relief well to halt the flow of oil.

"This is a 'think about it when it happens' plan," Bea said.

During cross-examination by a BP lawyer, Bea acknowledged that other offshore operators had virtually identical plans for responding to a spill. Other companies didn't have capping stacks suitable for deep-water usage, either, Bea said.