UC Santa Cruz researchers began moving back into the Sinsheimer labs Tuesday, a month after a devastating fire, but biology professor Manny Ares is still wondering what caused the pre-dawn blaze.

"I haven’t heard anything that makes sense," said Ares, whose lab on the fourth floor must be rebuilt.

Investigators believe the fire started under a work bench. A preliminary report theorized that waste baskets could have contained paper towels with flammable liquids or that lab equipment was left on or malfunctioned.

Ares, 46, who has been at UCSC since 1987 and specializes in genetic research, said he can’t figure it out.

"A lot of what we do is like cooking," he said, going over the list of what sat on the counter: a computer, a spectrophotometer that shines light on the research at hand, a water bath, and a centrifuge to separate materials.

None of the equipment was bigger than a coffeemaker, and Ares insisted there were no high-voltage appliances, flammable materials or overburdened extension cords — "nothing you would imagine would burst into flame," he said.

UCSC Fire Chief Charles Hernandez, who is waiting for a final report, said he understands Ares’ frustration.

"It’s easier to deal with if you know the exact cause," Hernandez said. "You can say, ‘We won’t do that anymore.’ "

Damages have been estimated at up to $5 million.

Ares lost all of his equipment. His lab has been stripped to studs and concrete. Reconstruction is scheduled to start in April and take six to eight months.

The building, which cost $23 million and opened in 1987, will be brought up to code, but sprinklers aren’t part of the project. The building didn’t have sprinklers to begin with, and the state doesn’t provide money for retrofitting.

Hernandez said that’s not unusual. Older buildings throughout the UC system haven’t been retrofitted with sprinklers because of the expense.

There have been exceptions, however. At UCSC, housing administrators decided to retrofit dorms with sprinklers after a fire at a Porter College dorm in 1993, spending money that might otherwise have gone for carpeting or other amenities.

Planners also gave in when Hernandez demanded sprinklers be installed at McHenry Library when an addition doubles the size of the building.

Graduate students working with Ares lost their research as well as books and personal items. Valerie Welch took the biggest hit. Tyson Clark and Lisa Trevino lost some of their data, and Sam Gu lost time that couldn’t be spent on research.

The disruption has been worse than in the 1989 earthquake, when Ares was displaced for three days. But he has experienced the same feeling of people helping each other cope with disaster.

The University of Washington, which had replicated a special material UCSC had sent to its researchers, sent some back to Santa Cruz. UC San Francisco opened its doors to Welch so she could restore some research she lost.

And UCSC staff rearranged teaching labs to accommodate lab work by Sinsheimer researchers displaced by the fire.

Even so, researchers are eager to get back in their own space, even if it is only temporary. Ares said the Sinsheimer building has an open architecture that makes it easier for people to share research equipment.

"We’ll be able to operate at almost 100 percent," he said.

Friends are surprised Ares is taking the loss so well.

Here’s the reason: When he arrived at the fire scene, Chancellor M.R.C. Greenwood handed him her cell phone so he could call everyone who worked in the lab to make sure no one was inside.

"That’s the important thing," Ares said.

"No one was hurt."

Contact Jondi Gumz at jgumz@santa-cruz.com.