INDEPENDENCE, Mo. (AP) — Prosecutors have dropped charges against a man who was accused of fatally shooting a pregnant woman after she went to a suburban Kansas City mall to shop for baby clothes.

Michael Mansur, a spokesperson for the Jackson County prosecutor’s office, said Monday that not enough evidence had been obtained to prove the charges filed against the 21-year-old beyond a reasonable doubt.

Authorities believe there were multiple people who fired shots after two groups got into an argument at Independence Center on Nov. 10. Four people were shot, including 19-year-old Karla Brown, who was four months pregnant when she was killed.

Hampering the investigation was the fact that police were not able to find any of the guns that were used, forcing investigators to rely on gun casings and blood spatter, the Kansas City Star reported.

The 21-year-old man initially was charged with three counts of unlawful use of a weapon and three counts of armed criminal action in the shooting. One of the charges later was upgraded to second-degree murder.

But Mansur told The Kansas City Star that the county’s investigation will continue, and a different set of charges could still follow.

Courts records said the 21-year-old and Brown entered the mall with different groups of people. Brown dropped back and sat in a chair before a disagreement between the groups turned violent. Brown was shot in the head and died about a week later.

At the time of the shooting, the 21-year-old told investigators he had been present at the mall but was not armed.