Obama is not only a U.S. senator from Illinois, but he is a creature of his adopted city, Chicago. His identity -- as we've been reminded in the controversy over his incendiary pastor -- is bound together with the city's South Side, where the streets from one neighborhood to the next are a stage for both the glorious and the tragic.

Amadou Cisse, from Senegal, was a graduate student at the University of Chicago, located in the South Side community of Hyde Park. At 29, he had completed his doctoral dissertation in chemistry -- his topic had to do with molecules migrating through thin polymer films -- and had just passed the required oral defense of his work.

He was days from the ceremony at which he would receive his degree when, on Nov. 19, while returning to his apartment just south of the campus, he was gunned down in a late-night street robbery.

The murder naturally unloosed waves of grief, fear and anger in and around the university -- foreshadowing, it could be said, what happened when students at Duke and UNC-Chapel Hill were slain. Obama surely heard about the killing. He is, after all, a former member of the U. of C. law faculty, and he and his wife lived in Hyde Park, which was in his district when he was a state senator.

According to the university (its magazine comes to my house because one of my sons was an undergraduate there), this was the first time one of its students had died of a violent crime in or near the campus since 1977. Still, safety is an ever-present concern. And the death of Amadou Cisse surely resonated with Obama as he campaigned for president with his message of hope and healing.

Hyde Park itself, about five miles south of downtown Chicago, is an intensely multicultural place whose character seems to mirror Obama's biracial heritage -- perhaps even the innate tension between the two strands of his ethnicity. The university keeps the Hyde Park economy afloat if not thriving.

But within the greater South Side, prosperity is the exception rather than the rule, by far. That of course has been a long-standing concern at the university, which has engaged in a host of community outreach and uplift efforts over the years.

A main focus has been on the neighborhood just south of the campus, Woodlawn. As a university official noted in the magazine, Woodlawn's population after 1960 plummeted as most white and middle-class black residents left. Those who remained -- 97 percent non-white in 2000 -- were ravaged by poverty and crime.

The University of Chicago campus has a physical feature that is both a blessing and somewhat of a curse. It is the Midway, or the Midway Plaisance as it is formally known, a long, open mall, oriented east-to-west, that dates from the grand Columbian Exposition of 1893 and the university's earliest days.

Most of the campus lies north of the Midway. Its signature Gothic facade, with buildings endowed by John D. Rockefeller, stretches along the mall's northern boundary on E. 59th Street, perpendicular to Lake Michigan.

But the campus has a smaller south-of-the-Midway portion as well. The park, delightful when the weather is warm and bright, becomes a forbidding barrier during frigid, blustery Chicago winters, or after dark. The effect is to make the southern part of campus sort of an outpost. It is within the gravitational field of Woodlawn as much as Hyde Park. Cisse died at the corner of E. 61st Street and S. Ellis Avenue, only four blocks from the university president's office farther up Ellis, but across the Midway.

The university has had some success stabilizing Woodlawn's northern edge. The commercial corridor on 63rd Street, however, was pure urban grit the last time I saw it. South of there range neighborhoods where the black liberation theology proclaimed by the Rev. Jeremiah Wright at Trinity United Church of Christ, on 95th Street, has an understandable appeal.

Understandable, that is, if it helps people who have in fact been oppressed rise above grievance and forthrightly confront the social ills that plague so many poor black communities.

Obama, the Trinity congregant, sought last week to loosen without breaking his ties to the recently retired Wright. But as he continues to face questions about his judgment and beliefs, he might draw on the tragedy at 61st and Ellis as an example of the tensions that can explode amid the grip of urban dysfunction. Wright's theology may be a sign of desperation, but the community to which he speaks is desperate as well. Who was it that failed the four young men -- ages 21, 17, 17 and 16 -- arrested in Amadou Cisse's murder? Probably not Trinity U.C.C.