Authorities said they are investigating whether Uber driver Jason Brian Dalton may have given a harrowing ride to a passenger shortly before embarking on a shooting spree in Kalamazoo, Mich., that killed six — and that they are looking into whether Dalton may have continued picking up fares in the middle of his rampage.

Ultimately, investigators may decide that there was no reliable way to predict that Dalton would, during a single shift on the job, morph from his identity as a driver into his role as a mass killer. Police say Dalton didn't have a criminal history.

An Uber spokesman confirmed Dalton had been working with the company and said he had passed a background check required for drivers employed by the company. The person declined to say how long Dalton had been driving for Uber.

The incident came just weeks after Uber settled two class-action lawsuits for $28.5 million after the company was accused of exaggerating the safety of its background checks. Despite using phrases such as "safest ride on the road" and "industry-leading background checks," the suits claimed, the company did not check drivers against the national sex-offender registry or employ fingerprint identification.

"We learned of systemic failures in Uber’s background checks," San Francisco District Attorney George Gascon said in reference to the lawsuits, according to Forbes. "We have learned they have drivers who are convicted sex offenders, thieves, burglars, kidnappers and a convicted murder."

"This is only really scratching the surface," he added.

At a news conference on Dec.9, 2014, California prosecutors announced a lawsuit against Uber over the ride-booking company's driver background checks. (Reuters)

Saturday's shooting spree apparently began with a bizarre twist.

One man told a local TV station that an Uber driver who looked like Dalton picked him up about 90 minutes before the shooting rampage began.

"We were driving through medians, driving through the lawn, speeding along and when we came to a stop, I jumped out the car and ran away," Matt Mellen told WWMT News. "He wouldn’t stop. He just kind of kept looking at me like, 'Don't you want to get to your friend’s house?' and I'm like, 'I want to get there alive.' "

Mellen said he contacted police and Uber about the wild ride. Then, he recognized the face after local media posted photos of the alleged shooter.

"I'm upset because I tried contacting Uber after I had talked to the police, saying that we needed to get this guy off the road," Mellen told WWMT.

Hundreds gathered for a vigil in Kalamazoo, Mich., on Feb. 21, to remember the victims of the deadly shooting rampage the day before. (Reuters)

Uber chief security officer Joe Sullivan said in a statement that the company is "horrified and heartbroken at the senseless violence in Kalamazoo."

"Our hearts and prayers are with the families of the victims of this devastating crime and those recovering from injuries," Sullivan said. "We have reached out to the police to help with their investigation in any way that we can."

Uber drivers without criminal histories have committed crimes before. Just to name a few, Uber drivers in recent years:

Have been involved in a racially motivated choking incident and an anti-gay assault.

Have been arrested for drunken driving at the Super Bowl.

Patrick Karajah, 26, a driver in Pacifica, Calif., had no criminal record. But in 2014, he pleaded guilty to felony charges of assault with a deadly weapon and battery with serious bodily injury. Officials said he struck a 25-year-old passenger in the head with a hammer, fracturing the man's skull, after an argument about the route Karajah was driving.

Steve Clark, a legal analyst and ex-prosecutor, told CNET that that incident raised questions about how well drivers were prepared to do their jobs.

"The question isn't only did he have a clean record but how well was he trained," Clark said. "Just doing a background check and saying, 'You're on the way,' is not enough. You need some guidelines saying, 'This is how you treat unruly passengers.' "

Uber has defended its screening process before.

In a detailed statement explaining its procedures in July, the company said that all drivers must undergo a screening process performed by Checkr, which Uber said is "nationally accredited by the National Association of Professional Background Screeners."

"People wanting to sign up as a driver-partner with Uber are required to provide detailed information, including their full name, date of birth, social security number, driver’s license number, a copy of their driver’s license, vehicle registration, insurance, and proof of a completed vehicle inspection," the statement said. "With the potential driver-partner’s approval, Checkr then looks into his or her background.  They run a social security trace to identify addresses associated with the potential driver-partner’s name during the past seven years, and then searches for his or her name and addresses in a series of national, state and local databases for convictions in the last seven years."

Critics say seven years doesn't peer far enough into a potential driver's past.

Drivers cited in the lawsuits had felony convictions as long ago as 1982, Forbes reported, for incidents as wide-ranging and kidnapping for ransom, assault with a firearm, robbery and committing lewd or lascivious acts against a child under 14. (You can read the entire list of crimes here).

The suits also claimed that Uber runs drivers' named through an incomplete sex-offender registry that is missing around 30,000 names in California.

"The background check process that Uber and Lyft are doing follows California law," Gascon said, according to Forbes. "The problem we have is the misleading information that is being provided by Uber."

The company claims that seven years "strikes the right balance" between protecting the public and offering "ex-offenders the chance to work and rehabilitate themselves."

At the same time, Uber's terms and conditions emphasize that passengers accept risk by riding in one of their vehicles.

"You understand, therefore, that by using the application and the service, you may be exposed to transportation that is potentially dangerous, offensive, harmful to minors, unsafe or otherwise objectionable," Uber's terms and conditions read, "and that you use the application and the service at your own risk."

Chris Dolan, an attorney who is representing a 6-year-old girl who was struck and killed by an Uber driver this year, told CNET that the company's fine print absolves the company of injury, accidents or a dangerous driver.

"It completely covers their a-- and says, 'We're not responsible for anything that happens to you, period,'" Dolan said. "It says, 'You can be raped, you can be killed, you can be murdered, and it's not our responsibility.'"

This post has been updated.