A co-worker of the man accused of plotting to shoot up the Long Beach Marriott told a judge Monday that he feared for his life as the man calmly walked him through his plan.

Juan Cruz said he was working with 37-year-old Rodolfo Montoya in a Marriott kitchen on Aug. 18 when Montoya confidently described how he wanted to murder the hotel’s human resources staff, other employees and even Cruz.

“That day, he told me he had a plan to go kill all of us,” Cruz said, speaking through a Spanish translator when he took the stand at a preliminary court hearing.

As Montoya laid out the plan, he showed Cruz pictures of a “machine gun” and a “chopped up body” he had on his phone, according to Cruz.

“He said that if the police would arrive, he had a bullet to put in his head and he was gonna do it to himself,” according to Cruz, who said he believed Montoya was serious because the plan was so detailed, down to which door Montoya would arrive through and which jacket he’d wear to help smuggle in a rifle.

Monday’s hearing was an early glimpse at the evidence authorities have against Montoya.

Montoya, wearing a white jail jumpsuit and handcuffs, listened quietly while another interpreter translated the proceedings for him. He is accused of plotting the shooting after losing some benefits and hotel reward points he had as part of his job.

At the end of the court date, Judge Richard M. Goul decided there was enough evidence to hold Montoya on felony charges of possession of an assault weapon, intimidating a witness and two counts of criminal threats. He’s pleaded not guilty and is being held on $500,000 bail.

Cruz said Montoya warned him not to tell anyone about their conversation. Cruz remembered him saying, “that if I was going to be a gossip, he was going to kill me.”

Nevertheless, Cruz said he told his boss, but it wasn’t until the next day that hotel staff called police, leading Montoya’s attorney to question whether the conversation actually inspired any real fear, which is a requirement for Montoya to be convicted of making threats.

On Aug. 20, police arrested Montoya and searched an RV in Huntington Beach where he lived.

One of the police officers at the scene testified Monday that the RV’s interior was in disarray, full of “clutter, junk, clothing” and other stuff.

But, he said, in the RV’s bedroom they found guns and ammunition, including a pistol tucked under a rolled-up blanket Montoya appeared to use for a pillow.

The collection of weapons also included two more handguns, three rifles, a shotgun and more than a dozen cans of ammo, police said previously.

All but one of the guns were legally owned, police said in court Monday.

The semi-auto AR-15 rifle laid out on the bed was an assault weapon as defined by California law, in part because it had tactical equipment like a telescoping stock, pistol grip and flash suppressor, Det. Henry Vong testified.

In an interview with police, Montoya said he knew the gun was banned in California, but he was in the process of modifying it to make it legal, Det. Juan Carlos Reyes said from the stand.

In court documents, authorities have said Montoya “had the motive, means, and intention to carry out a mass shooting of employees and guests at the Long Beach Marriott Hotel,” at  ‎4700 Airport Plaza Drive.

Because of Goul’s ruling Monday, Montoya will continue to be held in custody until he faces a full trial or makes bail.