Nichols is in prison for the deaths of eight law enforcement officers who were among the victims of the blast. District Attorney Bob Macy had long promised to file state charges for the deaths of the 160 other people killed when a truck bomb tore through the nine-story office building.
Macy filed 163 counts against Nichols. In addition to the 160 first-degree murder charges, he accused Nichols of first-degree manslaughter for the death of an unborn child, conspiracy to commit murder and aiding and counseling in the placing of a substance or bomb near a public building.
"It will take a year to get to trial," Macy said in a news conference after he filed the charges.
"We are receiving excellent cooperation from the federal government," he said, referring to the evidence and materials gathered in the federal case.
Macy said it was a relief to have the charges filed. "Now the work really begins," he said.
In December 1997 Nichols was convicted on federal charges of conspiring to bomb the building and murdering eight federal officers who died in the April 19, 1995 explosion.
Macy has also promised a state trial for Nichols' partner in crime Timothy McVeigh. But he said he would proceed with the case against Nichols first and wait to see how McVeigh fares on his appeal of his federal death penalty.
Federal prosecutors contended in the trials of both McVeigh and Nichols that the men worked side by side to acquire the ingredients and build the 4,000-pound fuel-and-fertilizer bomb. They said the bombing was a twisted plot to avenge the FBI siege at Waco that had occurred exactly two years earlier.
Macy anticipates a series of court battles on double jeopardy and speedy trial points, making the road to trial a long one.