Members of Turkish President Recep Tayyip Erdogan’s security detail are shown acting during the violence last year when Erdogan was in Washington. (Voice of America/AP)

Prosecutors in recent months have dropped assault charges against several security guards for Turkish President Recep Tayyip Erdogan who were allegedly involved in a melee last May outside the Turkish ambassador's residence in Washington.

Video of the incident, which showed guards for the visiting Turkish president charging and beating protesters who had gathered outside the Sheridan Circle residence, sparked international condemnation.

Fifteen guards were indicted in July, but federal prosecutors in the District dismissed charges against four members of Erdogan’s security detail in November. Last month, they dropped the cases against seven others.

Charges against four guards remain active, though the men left the country soon after the incident and experts have said it is unlikely they will ever be put on trial.

The Wall Street Journal first reported the latest dismissals.

A spokesman for the U.S. attorney’s office in the District declined to say why the cases were dropped.

According to the July indictment, the guards faced a variety of charges, including conspiracy and assault. Prosecutors said the men had “assaulted and kicked protesters who were assembled in front of the embassy.”

Officials had previously said the men were identified with the help of the State Department, which matched surveillance video to entry visas and passports.

Erdogan had immediately denounced the charges, blasting D.C. law enforcement and arguing the demonstrators were affiliated with a terrorist group. The Turkish Foreign Ministry summoned the U.S. ambassador in Ankara after the cases were announced and said in a statement after the incident that the decision to file the charges “lacks legal basis.”

One person familiar with the case, who was not authorized to comment publicly about the decision and spoke on the condition of anonymity, said prosecutors had questioned whether there was sufficient evidence to move forward.

Charges and arrest warrants remain for four guards — Ismail Dalkiran, Servet Erkan, Ahmet Karabay and Mehmet Sarman.

According to the indictment, Sarman, along with the guards whose charges were eventually dropped, assaulted and kicked a protester, as well as American law enforcement officers who were trying to intervene. He is also charged with pushing one protester to the ground and punching and kicking another protester.

Karabay and Dalkiran are accused of ignoring orders from D.C. police officers who told them to stop the assaults and return to the sidewalk. Karabay was also accused of communicating with other security guards via earpieces and then kicking and punching a victim.

Dalkiran was also charged with assaulting and threatening another victim “in a menacing manner.”

Erkan was charged with recklessly causing significant bodily injury to one victim and charged with using a dangerous weapon, a shod foot, on another person.

On April 5, two U.S. citizens who were not part Erdogan’s security team, Sinan Narin and Eyup Yildirim, are scheduled to be sentenced in D.C. Superior Court after pleading guilty to felony assault charges in the incident.