MIAMI -

A 21-year-old man pleaded not guilty to fatally shooting his 17-year-old girlfriend.

Police arrested Yoan Raul Dominguez on March 10 in connection with the murder of Genesis Fonseca. He was charged with second-degree murder.

During his arraignment Monday, a family member of Fonseca lunged at Dominguez but was stopped by a bailiff.

Dominguez shot and killed Fonseca at her mother's apartment in Hialeah on March 9, police say. The two had been dating for four months.

Genesis Fonseca, Yoan Raul Dominguez

Police say Dominguez left the apartment after the shooting. According to an arrest report, on separate occasions, he told his mother and a close family friend that he killed his girlfriend.

It's unclear what led up to the shooting.

Police recovered a .38-caliber revolver from Dominguez when he was arrested in Miami.

When Dominguez was arrested, he was out on bail on a prior aggravated battery charge.