The murders have sparked concerns over international taxi firm Uber, which offers cut price fares by using members of the public as drivers.
Critics have raised fears over the drivers as they are not licensed by the council to drive taxicabs.
Uber security chief Joe Sullivan said Uber became aware at some point on Saturday of Dalton’s driving after receiving several complaints from passengers, including one about dangerous and erratic driving.
One passenger called the police to report Dalton was driving erratically and tried to contact Uber more than an hour before the shootings began.
The incident has led to serious questions regarding Uber’s safety measures after the firm agreed to more than £20million to settle two lawsuits earlier this month that claimed it misled customers about safety procedures and fees.
Uber is also facing another lawsuit by district attorneys in Los Angeles and San Francisco for failing to prevent the hiring of several criminals.
Several Uber drivers have also been accused of raping passengers in the US and India. A driver in Massachusetts was sentenced to prison last year after being found guilty of raping a female passenger.
Following the shooting Uber has been forced to defend its screening of drivers, arguing the company had no reason to believe Dalton was a danger to passengers.
Dalton cleared a background check and was approved to be a driver on January 25,.
Dalton, who had no prior criminal record, had driven more than 100 fares and had a rating of 4.73 stars out of a possible five.
Ed Davis, a former police commissioner who serves on Uber’s safety advisory board, said the company’s system is “extremely safe”.
Mr Davis added: “A background check is just that. It does not foresee the future.”
Matthew Daus, a former taxi commissioner and transportation lawyer, said Uber’s background checks compare names to public court records and are far less effective than fingerprint checks that access FBI criminal history database.
Mourners attended a service in a local church in Kalamazoo to honour the victims, including a father and son.