Saturday’s horror-movie episode on the MacArthur Causeway brought together two troubled men, one who was struggling to get his life on track, another who had given up trying.

Rudy Eugene, 31, had been seeking spiritual guidance in Scripture. On May 24, two days before he viciously attacked a homeless man named Ronald Edward Poppo, chewing off much of his face, Eugene attended a Bible-study session at a friend’s North Miami Beach home.

Recently, Eugene posted a verse from Psalm 59 on his Facebook page: “Deliver me from my enemies, O my Lord; Defend me from those who rise up against me. For the Lord God is my defense. . . .”

Friend Bobby Chery said he, Eugene and another friend discussed that day what they could do to become better men according to the word of God, and that Eugene vowed to give up marijuana.

That same Thursday, Miami police rousted Poppo from one of the last places he called home: the top floor of the parking garage at Jungle Island, the Watson Island botanical and wildlife attraction.

Outreach workers from the Miami Homeless Assistance Program found him there and offered help, said Ronald Book, chairman of the Miami-Dade County Homeless Trust.

But after Poppo became “belligerent and aggressive,” the outreach team called police. Officers issued Poppo, who had turned 65 a week earlier, a “trespassing after warning” citation.

“He grabbed his box of stuff and went off,” said Book. Outreach workers reported he was “cursing and claiming discrimination.”

About 2 p.m. Saturday, a naked Rudy Eugene grabbed Poppo near the causeway’s western end, stripped off his clothes, beat him, bit him and gnawed off his face.

More than 15 minutes into the attack, a police officer arrived and shot Eugene to death. Poppo remains in critical condition at Jackson Memorial Hospital’s Ryder Trauma Center.

The crazed assault shocked almost everyone who knew Eugene.

Johansen Aurelus, a childhood friend, called Eugene “preacher” because he liked sharing Bible verses with friends and kept his Bible handy.

Aurelus attended Bethel Baptist Church with Eugene when they were teens. Back then, Aurelus said, Eugene would ask questions about the pastor’s sermons and how they applied to his life.

Over the years, Eugene had some run-ins with the police for marijuana possession and a domestic dispute. Most recently, he had trouble holding a job, friends say.

Eugene’s stepfather, Melimon Charles of North Miami, said Eugene “is not the kind of devil who goes out and kills people like they are showing on the news. He’s a fine boy. He was raised in the church. He was in the choir.”

Trouble may have started about the time Eugene learned Charles was not his biological father, in ninth or tenth grade, although Charles had been with Eugene’s mother, Ruth, since the boy was 2.

Rudy “was angry because he was looking for his father,” Charles said. “His father passed away and he didn’t know. And I didn’t know anything about it. I didn’t even have a picture to show him.”

Soon after, he said, Eugene accepted “the truth and we were doing fine.”

But at 17, Eugene moved out of his home, without telling his stepfather. He transferred from North Miami Beach High School to North Miami High.