Twelve grim days after a policeman in Ferguson, Missouri, gunned down Michael Brown, an unarmed 18-year-old, there finally is some welcome news.

Attorney General Eric Holder, the nation’s top law enforcement officer, has arrived on the scene with a presidential mandate to pursue justice for the Brown family and the community. There is halting progress in the vital work of determining exactly what happened in the moments leading up to Brown’s death. The incidents of violence triggered by the shooting seem to be subsiding.

And perhaps most important, the country is absorbing another reminder of the yawning gap between our ideals of individual liberty, equal opportunity and racial harmony and the reality of life in thousands of communities across the country.

So what happens now?

In the short term, local authorities, Attorney General Holder, and the Obama administration must deliver a thorough, credible, transparent investigation and vigorous prosecution of any offense it uncovers.

Holder has an unenviable burden; he must demonstrate that the administration will neither tolerate police brutality nor minimize the challenges faced by cops on the beat.

The available evidence appears damning to Ferguson Patrolman Darren Wilson; if it holds up, he must be called to account. Holder and the Justice Department will do the nation a tremendous service if they can begin to reverse the sense among African-Americans that police are an arrogant, out-of-control occupying force in their communities.

But however culpable Wilson appears, Holder must see to it that any prosecution gives him the presumption of innocence our justice system guarantees – though often fails to deliver – to every criminal suspect. And he must reassure good cops across the country that they’re not being blamed for the misdeeds of a few.

Beyond that, it’s up to elected officials in Ferguson and communities across the country, and to the people who live in them, to address the deep-seated societal problems that fueled the explosion of outrage following the Brown shooting.

For starters, elected officials and community leaders must get busy fielding police departments that reflect their populations. The Justice Department reports that more than 1 in 4 police officers nationally are members of racial or ethnic minority groups, but hundreds of localities like Ferguson still have few if any officers of color. There are just three African-Americans among 50 officers in Ferguson but 66 percent of the city’s residents are black.

Even when police departments look like their communities, there will be tensions between officers and the people they serve. So police everywhere — and particularly in communities of color — must work as hard to build rapport with residents as to track down suspected offenders.

And while officers called to a mass shooting like the one at Sandy Hook Elementary may have legitimate need for assault rifles and tear gas, the everyday use of such gear sends residents an ominous message: you’re the enemy.  News that Defense Secretary Chuck Hagel will review shipments of surplus military weapons to local police is welcome; Congress and the Pentagon should put strict limits on the use of that equipment.

Perhaps the toughest challenges revealed once again by the Brown shooting are economic and political. Fortune magazine reported last week that the median household income in metropolitan St. Louis, including Ferguson, is $75,000. But the median in majority-black Ferguson itself is just $44,000. And while white unemployment in the area is slightly more than 6 percent, the jobless rate among African-Americans tops 26 percent.

“Studies link income inequality to higher infant mortality rates, higher crime rates, and lower economic growth” Fortune observed. The fact that violent protests have erupted in a community like Ferguson, where inequality is so dramatic “is not a coincidence,” the magazine asserted.

To prevent more Fergusons, the nation must attack such inequality. Incentive programs that bring good jobs with solid career prospects to young people of color would be a good start, along with major investments in education and job training. And to give immediate relief to the folks who stock shelves at Walmart or flip burgers at McDonalds, we need Congress to raise the minimum wage to at least $10.10 and states and localities to adopt a living wage of $15.

Politically, Congress and state legislatures must attack barriers to voter participation and instead take proactive steps to increase registration and turnout. That means repealing unneeded voter ID requirements, increasing registration opportunities including Election Day registration, providing additional early voting opportunities, and passing laws restoring the rights for citizens with felony convictions.

Just as important, residents in communities like Ferguson must put aside their resentments of white-dominated political systems – however justified by history — and get engaged. Despite the city’s substantial black majority, Ferguson’s six-member city council has just one African-American, and in municipal elections this year only 12.3 percent of eligible voters bothered to cast ballots.

“I think there is a huge distrust in the system,” said Leslie Broadnax, a Ferguson native and African-American who lost to a white candidate in her bid to become St. Louis County’s chief prosecutor. “Many blacks think: ‘Well it’s not going to matter anyway, so my one vote doesn’t count,’” she told MSNBC. “Well, if you get an entire community to individually feel that way, collectively we’ve already lost.”

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(This post first appeared in The Huffington Post)