Lorenzo Harris, MDOC 2012 mugshot

DETROIT, MI -- Key evidence related to a Detroit police chase of a Chevrolet Camaro that ended with the deaths of two siblings and injuries to four others on June 24 doesn't exist.

Detroit Police Chief James Craig says the "older, marked scout car" occupied by three of his Special Operations officers had an inoperable dash-cam system. Police never found the gun they said one of the suspects appeared to have and that prompted the chase reaching up to 70 mph through an east side Detroit neighborhood.

However, Craig told media a witness at the scene reported seeing one of the suspects with a weapon after the crash, according to the Associated Press.

The unit's supervisor attempted to radio the cruiser to call off the chase three times before the crash, Craig said this week, adding the incident is still under investigation.

Police say the chase through residential streets lasted under 75 seconds.

It ended when the Camaro left the roadway, fatally struck two children -- Michael A. Jackson, 6; and Makiah Jackson, 3 -- continued and continued until striking the porch of a home, along the way additionally injuring a 23-year-old woman and three other children, 3, 5 and 7.

Detroit police arrested the driver, Lorenzo Harris, 29, a parole absconder with a 2006 conviction for possession of methamphetamine who fled the scene after the crash.

He is now charged with 16 crimes, including two counts of second-degree murder, which carries up to a life sentence.

Harris has prior felony convictions for receiving a stolen vehicle, firearms violations and resisting or obstructing a police officer.

Harris's injured passenger, Frazier Reese, hasn't been charged.

The chase drew criticism from neighbors and activists, including Ron Scott's Citizens Against Police Brutality, and most recently Oakland, Calif.-based Color of Change, a civil rights organization that advocates for black citizens.

"At a time when the country is grappling with how to end systemic discriminatory police violence and vigilante terrorism targeting Black communities, this tragic loss of life creates even greater urgency to implement widespread changes to policing," Color of Change Director Rashad Robinson said in a prepared statement Wednesday. "Independent oversight and officer discipline are critical for transforming a culture of policing that favors secrecy, violence and impunity over transparency and public accountability.

"As we have seen time and time again, police and local prosecutors are unable to hold their own accountable."

The organization is calling for an external review of the crash.

Ex-Detroit Police Chief Ralph Godbee commented publicly on the incident during an appearance on WJBK-TV's "Let it Rip" last week.

"You've got to consider the time of day, you've got to consider the weather conditions, you also have to contemplate school is out," Godbee said. "There are kids all over the place. That neighborhood is densely populated.

"If I'm Chief Craig, the question i want to know is, number one, was that a fully-marked, fully-uniformed unit ... Number two, how long were they following the car before they initiated the chase."

According to Gina Damron of the Detroit Free Press, the department police states: "officers shall utilize in-car video equipment for all vehicular pursuits," and a supervisor is to remove the in-car videotape and place it on evidence following a collision "if any of the involved vehicles were so equipped."

Godbee says he'd look at the officers' past reports.

"Is this just a narrative as an excuse for a chase, because when the department was put under two federal consent judgments, one scathing criticism was that the narrative was the same all the time," the ex-chief said. "Saw a gun, started to chase, and then you don't find a gun."

Godbee said with two kids dead, "the cost is too high" and you have to ask the tough questions.

A GoFundMe online fundraiser for the victims' family raised $18,745 of the $20,000 goal as of Wednesday evening.

There was a visitation fo the children from noon to 8 p.m. Wednesday.