Transocean employees should have done more to detect signs of trouble before the company's drilling rig exploded in the Gulf of Mexico in 2010, killing 11 workers and triggering the United States' worst offshore oil spill, the company's chief executive testified Tuesday.

Transocean Ltd. president and CEO Steven Newman said the Swiss-based drilling company agreed in January to plead guilty to a criminal charge of violating the Clean Water Act because its employees on the Deepwater Horizon played a role in botching a crucial safety test before the blowout of BP's Macondo well.

"Do you blame the crew that night?" Transocean attorney Brad Brian asked Newman on the 14th day of a trial designed to determine the causes of BP's well blowout and to assign fault to the companies involved.

"Do I blame the crew? Do I wish the crew would have done more? Absolutely. I am not sure that that's the same emotional content as blame," Newman said.

Newman, however, said BP ultimately was responsible for deciding how to perform the safety test and for determining whether it was successful.

"The responsibility that our crew has in a situation like that is to line the test up, to make sure that the lines and the valves and the gauges are the way they're supposed to be," Newman said.

No Transocean employees charged

Two BP rig supervisors, Robert Kaluza and Donald Vidrine, are charged with manslaughter in the 11 rig workers' deaths and await a separate trial. An indictment last year accused Kaluza and Vidrine of disregarding abnormally high pressure readings during the safety test.

No Transocean employees have been charged with crimes, but the company pleaded guilty to the misdemeanor charge in February and agreed to pay $1.4 billion in criminal and civil penalties as part of a settlement with the Justice Department.

Newman was in Geneva, Switzerland, when the rig exploded April 20, 2010. When another company executive called to tell him the rig was on fire and was being evacuated, Newman could tell from the man's voice that "something was terribly wrong."

"I kept telling myself that the first phone call associated with an incident is always as full of misinformation as it is of information, and so I just kept telling myself it couldn't be that bad," he recalled.

Newman immediately flew to Houston to meet with Transocean and BP officials before traveling to New Orleans, where he met with Coast Guard officials and relatives of workers who died in the blast.

Newman touted the company's safety culture, saying any rig worker is empowered to call a halt to a drilling operation. If a worker sees any cause for concern, he said, "You not only have the right but the obligation to call a timeout."

"Safety is one of our core values," Newman said. "I think it is fundamental to what we do. "