In a strange twist, the suspect in the Kalamazoo killing spree is suing Uber for $10 million, claiming his work as an Uber driver caused him "psychological damage."

Jason Dalton, 45, is accused of killing six people and injuring two others in the western Michigan city over five hours on February 20 while picking up fares for Uber.

In a handwritten complaint filed Tuesday in the U.S. District Court for Eastern Michigan, Dalton wrote that Uber "discriminates against my mental health."

"I'm currently in prison because of Uber," he wrote. "Uber doesn't care about its drivers, we are peasants and pawn pieces to Uber's bottom line." He said his wife is seeking a divorce "because of Uber."

Dalton claims in the suit that he's been a contract worker for Uber for "years," and that he wasn't invited to corporate parties or given a Christmas bonus. But Uber chief security officer Joe Sullivan said Dalton began working for the company in late January 2016.

"It's hard to know how to respond to someone who refuses to take responsibility for his own actions," said an Uber spokesperson in a statement sent to CNNMoney. "Our hearts go out to the victims' families who have to live with the consequences of his terrible crimes."

Dalton said he wants $10 million to compensate him for "punitive damages and emotional distress."

Uber, the most valuable privately-held startup in the world, is currently valued at $51 billion, according to CB Insights.

The news of Dalton's suit was reported earlier by the San Francisco Business Times.

Dalton has previously told investigators he was reluctant to talk because he didn't want to come across as a "crazy person," according to documents released Monday and published by CNN affiliate WDIV-TV in Detroit. He went on to tell investigators the Uber app made him "like a puppet" and that it would "take over your whole body."

Police have said he does not have a history of mental health issues. Earlier this month, a prosecutor said Dalton would undergo a psychiatric evaluation to determine his competence to stand trial.

-- CNN's Joshua Berlinger and Dana Ford and CNNMoney's Ahiza Garcia contributed to this report.