Friends and family attend the memorial service, on July 10, 2013, in Washington, D.C., for Howard University student Omar Sykes, who was fatally shot in an attempted robbery. (Jahi Chikwendiu/The Washington Post)

A 26-year-old man was arrested Tuesday in the July killing of a Howard University senior who was shot just outside the Northwest Washington campus in what D.C. police have termed a random robbery attempt.

Rasdavid Lagarde of Northeast Washington was charged with first-degree murder while armed and is scheduled to be arraigned in D.C. Superior Court on Wednesday. His relatives could not be reached Tuesday evening.

The July 4 killing of Omar Sykes, 22, a business marketing major whose mother works in the Foreign Service, stunned the Northwest Washington campus.

“We would like to thank the Metropolitan Police Department and the entire community for their tireless efforts to resolve this case and bring the responsible person to justice,” Howard University spokeswoman Kerry-Ann Hamilton said in a statement. “The Howard Community still mourns the loss of Omar Sykes, a young man of tremendous promise.”

Added Assistant D.C. Police Chief Peter Newsham: “I don’t think anything is more innocent than a young person coming to the District of Columbia to attend college. To lose him in this way is a tragedy. We’re hopeful this will give the family some sort of closure.”

The suspect’s mother, Terri Lagarde, said her son had recently returned after attending auto mechanics school in Texas to learn how to fix high-performance cars. He lost a job and became homeless, she said, and returned to the District.

“I feel really bad about what happened,” she said. “I never thought I would be in this position. I mourn for any mother’s child.”

Sykes was shot about 11:30 p.m. at Georgia Ave. and Fairmont St. Police said two attackers with handguns approached him and another student and announced a robbery. Authorities said they still have not determined whether anything was taken from Sykes; his wallet remains missing, police said, but it’s unclear whether it was taken or lost in the mayhem.

A police official with knowledge of the investigation said a witness told police that he heard the suspect say he was involved in the robbery. The official, who spoke on the condition of anonymity because details from court documents have not been made public, said detectives then traced the suspect’s cellphone to the location and time of the robbery.

Sykes was the leader of Howard’s chapter of Alpha Phi Omega, a co-ed service fraternity. Friends packed a campus vigil held at Howard’s Andrew Rankin Memorial Chapel a day after his death.

Relatives of Sykes have not spoken publicly about the killing, limiting their words to a statement expressing their sadness for the loss and appreciation to the Howard University campus. A scholarship in Sykes’s name has been started through the American Foreign Service Association.

Sykes’s mother, Sherry Zalika Sykes, is serving in Mozambique, according to the scholarship Web site. His father, Adam Sykes, is from Dar es Salaam, Tanzania. The Web site says the younger Sykes grew up in California, Tanzania, Nigeria, Ethi­o­pia and South Africa. A tribute to him on the site says, “He was well known for his polite, open hearted way with everyone he met, and his passion for making the world a better place through music, art and social action.”

Jennifer Jenkins contributed to this report.