A judge is considering whether to allow statements at trial made by an Uber driver in Michigan accused of fatally shooting six strangers in between picking up riders.

Kalamazoo County Circuit Court Judge Alexander Lipsey said Thursday that he would rule by April 20 after hearing arguments.

Police have quoted the suspect, Jason Dalton, as saying a "devil figure" on Uber's app was controlling him on the night of the shootings around Kalamazoo in southwestern Michigan.

Related: Judge to Jason Dalton's attorneys: Back up your insanity defense

Dalton's attorney wants the statements suppressed, saying investigators violated his client's rights against self-incrimination.

Prosecutors say Dalton waived his Fifth Amendment rights when he started a conversation about the police investigation.

Dalton faces murder, assault with intent to murder and gun charges in the Feb. 20, 2016, shootings that also wounded two people. That trial will start in June.

After hearing legal arguments from both parties and testimony from witnesses regarding the admissibility of Dalton's statements, the judge said he would make his decision of whether or not to suppress the statements by April 20.