BRUSSELS (AP) — A French citizen charged with “terrorist murder” for the slayings of four people at a Jewish museum in Belgium refused to testify at his trial Tuesday, saying he didn’t commit the killings but the court had barred witnesses who could have spoken on his behalf.

Mehdi Nemmouche, 33, is accused of carrying out one of the first attacks by an alleged extremist who returned to Europe after fighting in the Mideast. Defense lawyers claim Israeli intelligence agents opened fire at the museum in a targeted killing.

Nemmouche is charged with gunning down an Israeli couple and two museum workers with a revolver and an assault rifle on May 24, 2014. Police officers flanked him in the Brussels criminal court where he is being tried, their faces covered by balaclavas.

“For the moment, I do not want to talk,” Nemmouche told the presiding judge. “None of the people who could have helped me have been retained on the list of witnesses.”

Asked whether he killed the four victims, Nemmouche answered “No.” He did acknowledge transporting the guns that investigators said were used in the museum slayings.

Security camera video of the attack showed a gunman wearing a baseball cap shooting the Israeli couple at point blank range at the museum’s entrance. The shooter then walked down a corridor and fired into offices.

When his handgun jammed, he pulled out an assault rifle and sprayed the offices, which is where the two workers were killed. The whole attack unfolded over 82 seconds and the killer strode away.

Nemmouche later was captured in France while traveling on a bus to Marseille. He had the guns allegedly used in the museum killings with him. His lawyers claim he was forced to transport the weapons, but gave no details.

An alleged accomplice, Nacer Bendrer, 30, also appeared in court Tuesday. Prosecutors accuse Bendrer of supplying the guns to Nemmouche.

French authorities have alleged Nemmouche was one of the jihadists who kept four French journalists hostage until they were freed in April 2014 in Syria.

Prosecutors have said they think the museum attack was part of a disturbing trend among returned foreign fighters: Some radicalized Europeans who trained or fought with extremists such as the Islamic State group came home and committed mass killings, including the November 2015 Paris attacks and the Brussels suicide bombings four months later.

Defense lawyers claimed Tuesday the museum shootings were the work of Mossad agents who targeted the Israeli couple.

“The killing was not an attack by Islamic State, but a targeted execution by agents from Mossad,” said lawyer Virginie Taelman, adding that details explaining why would be provided later.

Defense lawyers asked Mossad officials to testify at the trial but their request was rejected.

The defense urged the 12-person jury to acquit Nemmouche, saying none of his DNA was found at the scene or on the trigger of the revolver even though the killer did not wear gloves.

“Traces of DNA would have to be found on the handle and on the door” to the offices the gunman tried to open at one point, defense lawyer Henri Laquay said.

He said the jurors must ask themselves “what certain proof has been provided that Mehdi Nemmouche pulled the trigger in the Jewish museum on May 24, 2014?”

Nemmouche’s DNA was found on the barrel of the handgun and on the assault rifle but his lawyers said it was from his handling the weapons in a bag he was carrying to Marseille. They also asserted that at least one security image of the attack had been manipulated.

The trial is scheduled to run until March 1.