A man who was arrested on suspicion of killing a newspaper vendor in San Francisco in January has had his case discharged pending further investigation, a district attorney's office spokesman said Wednesday.

Mark Anthony Cassell, 36, was arrested on March 13 on suspicion of murder for an incident that occurred at about 11 a.m. on Jan. 28 in front of 1 Post St. that resulted in the death of 77-year-old San Francisco Chronicle vendor Dallas Ayers.

Police had alleged that Cassell approached Ayers, wrapped his arms around Ayers' waist, picked him up and dropped him to the ground.

Ayers was taken to a hospital, where he succumbed to his injuries on Feb. 21.

Cassell was arrested after police from the department's Tenderloin station recognized him from a department-wide bulletin. He had a bench warrant out for his arrest on methamphetamine possession and petty theft charges.

However, prosecutors have declined to file murder charges against him for the time being, district attorney's office spokesman Alex Bastian said.

"We can only charge a case when we have a good-faith basis to believe we can prove the case beyond a reasonable doubt," Bastian said.

Cassell remains in custody on $10,000 bail on the drug and petty theft charges, sheriff's Chief Deputy Kathy Gorwood said.