The driver accused of killing four Pepperdine University sorority sisters in a crash in Southern California last week appeared Wednesday in court after he was arrested and charged with murder.

Fraser Bohm, 22, was initially charged with vehicular manslaughter after the fatal Oct. 17 crash on the Pacific Coast Highway, a notoriously dangerous stretch of roadway running through Malibu. Bohm was treated for minor injuries at a hospital and released while detectives continued to investigate the crash and gather more evidence, the Los Angeles County Sheriff's Department has said.

After presenting the case to the Los Angeles County District Attorney’s office, sheriff's detectives re-arrested Bohm on Tuesday on suspicion of four counts of murder, a week after the fatal crash.

Bohm pleaded not guilty on Wednesday during his first court appearance to the murder charges and four counts of gross vehicular manslaughter, Los Angeles County District Attorney George Gascón announced at a news conference. While investigators say they determined that Bohm had been speeding along the highway, the defendant’s attorney, Michael Kraut, has disputed how fast Bohm was driving and said he was fleeing another angry driver.

Bohm’s bail was first set at $8 million and was later lowered to $4 million, the district attorney’s office said.

"We want to assure the community that we are committed to seeking justice for those who have been taken from us too soon,” Gascón said in a statement.

In a statement, the sheriff's department said the new charges are a result of investigators "relentlessly working to ensure we get justice for the victims’ families."

"Our detectives worked diligently to compile all the evidence needed so they could file the maximum charges allowed under California law," the sheriff's department said in the statement. "Our thoughts are with each family, friends, and students of each victim during this difficult time."

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Pepperdine hosts memorial service for victims

The news of the charges came two days after Pepperdine University, a small private Christian university overlooking the Pacific Coast Highway, on Sunday hosted a memorial service to honor the four women killed in the crash.

The women, all of whom were seniors at the university and sisters in the Alpha Phi sorority, were identified as Niamh Rolston, Peyton Stewart, Asha Weir and Deslyn Williams. Two others were injured in the crash.

“Each departed student brought a unique gift and spirit to the University, and we deeply grieve the unfulfilled hopes and aspirations of our precious community members,” Connie Horton, vice president for Student Affairs, said in a statement.

Pepperdine has created a website for the community to share condolences, as well as a memorial fund for the women — students in the university’s Seaver College of Liberal Arts — to support their families and to one day establish scholarships in their names.

"This fund is a testament to the love and compassion of our Pepperdine community, and it is our collective opportunity to make a meaningful impact for all who are affected by this profound loss," the university said in a statement. "The Pepperdine community continues to hold the Rolston, Stewart, Weir, and Williams families and those dearest to them in their prayers."

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Bohm's attorney said he was being chased when crash happened

Bohm had been driving a dark colored BMW westbound on the Pacific Coast Highway when investigators say he lost control.

He then slammed into three parked vehicles and crashed into a group of nearby pedestrians which included the Pepperdine students, investigators said. It appeared Bohm had been driving at a high rate of speed prior to the crash, officials said, which has become recurring problem along the 21-mile stretch of the highway running through Malibu.

“We need to do something different,” Sheriff’s Capt. Jennifer Seetoo said at a news conference last week, noting the number of fatal crashes that have occurred throughout the years on the road. “We’ve got to work together as a community; there's too many people on this stretch of the highway that have been killed.”

Gascón said at a news conference that Bohm's car reached 104 mph in a 45 mph zone, which Bohm's attorney disputes.

Kraut also told The Associated Press that the crash occurred as Bohm was being chased following a road rage incident that began when a man in another car started shouting at him at a stop light.

“The guy comes into his lane, hits my client’s car with his car and forces him off the road,” Kraut told the Associated Press.

Los Angeles County Sheriff’s Sgt. Jim Arens said at the news conference that investigators had “no evidence” that the crash stemmed from a road rage incident.

If convicted as charged, Bohm will face the possibility of multiple life sentences, according to prosecutors.

Contributing: The Associated Press

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]