Pasadena police are searching for clues related to the mysterious Sunday morning shooting death of a 20-year-old Pasadena man.

Just before 4 a.m., police responded to calls that shots had been fired in the 500 block of East Orange Grove Boulevard, between Los Robles and Lake avenues. There they found Fortino Acevedo wounded and lying on the street. Acevido was rushed to Huntington Memorial Hospital, but died from his wounds about seven hours later.

Police spokeswoman Janet Pope said the motive for the murder remains unclear but does not appear to be gang-related.

“This is going to be a very slow investigation,” Pope said. “But it’s not going to be because we are not working on it, but because of the legwork. We have a lot of witnesses to interview.”

Police are asking those with information to call (626) 744-4517.