A former personal assistant to Aaron Hernandez said Tuesday at his double murder trial that he knew about verbal altercations the former New England Patriots star had at nightclubs.

“I know things have happened’’ in clubs, said Ryan McDonnell, who is also a childhood friend of Hernandez. “I can’t recall specific events.’’

McDonnell said there were “fans who praised him’’ at clubs, as well as “fans of other teams.’’ He said he “hardly ever’’ accompanied Hernandez to night spots.

McDonnell’s testimony was relevant because prosecutors say Hernandez, 27, had a minor altercation with Daniel de Abreu and Safiro Furtado at a Boston club before they were killed.

Hernandez has pleaded not guilty to charges of killing de Abreu and Furtado in a drive-by shooting in Boston’s South End in the early morning hours of July 16, 2012.

Hernandez is also charged with shooting Alexander Bradley, his former friend and marijuana supplier, in February 2013 in an effort to silence him about the killings.

McDonnell testified Tuesday that he and Hernandez vacationed in Costa Rica during the same month as the double murder.

He said they first met in middle school and reconnected after the Patriots drafted Hernandez and he returned to New England.

They spoke daily over the phone, he said, and Hernandez eventually hired McDonnell as his assistant.

“We were super close,’’ McDonnell said.

He said Hernandez and Bradley appeared to be good friends as well.

Bradley, currently jailed in Connecticut for an unrelated club shooting, testified last week that he was behind the wheel of a Toyota 4Runner at a stop light when Hernandez reached across him and fired into the victims’ BMW.

He also said Hernandez shot him in an SUV in South Florida early on Feb. 13, 2013 after he and Hernandez left a Miami-area strip club with other men, and that he was pushed out of the vehicle and left for dead.

Jurors on Tuesday heard from two men who rode in the SUV with Hernandez and Bradley.

One of the men, Tyrone Crawford, 25, testified that the group dropped him off at a housing complex to meet his father after they left the club.

Once there, Crawford said, he realized he had left his phone in the SUV. He said his father dropped him off at the home of the girlfriend of Je’rrelle Pierre, the man he said he thought had been driving the SUV, so he could retrieve the device.

By then it was later in the morning on Feb. 13, after Bradley was allegedly shot and pushed from the vehicle.

Crawford testified that when he got back in the SUV to pick up his phone, he noticed everyone from the club except Bradley.

“Aaron’s friend wasn’t in there,’’ Crawford said.

Crawford told Jose Baez, a lawyer for Hernandez, on cross-examination that he did a lot of drugs that week and frequently passed out.

Baez asked if it was possible that Crawford may have been “pooling information from different nights’’ while testifying about the night of the 12th and early morning of the 13th.

“I would say yes,’’ Crawford said.

Pierre took the stand after Crawford and said he could not recall if he even went to the club with everyone that night.

“I been [sic] hospitalized like two times, sir, so my memory is not good,’’ Pierre said to prosecutor Mark Lee, adding that one hospitalization came after he was shot in a separate incident.

Pierre did say, however, that he remembered spending the night after the Bradley shooting with Deonte Thompson, then a receiver for the Baltimore Ravens, and Thompson’s girlfriend in Miami.

Thompson, Hernandez’s former teammate at the University of Florida, had invited Hernandez to Florida for a party on Feb. 8 to celebrate the Ravens’ recent Super Bowl victory.

Hernandez is already serving a life sentence for the June 2013 fatal shooting of Odin Lloyd. An appeal of his murder conviction in that case will be heard at a later date.

On Tuesday, McDonnell also deciphered lettering tattooed on Hernandez’s hand that reads CBS/WBS/IWBTG.

McDonnell said the letters were an acronym for “Can’t be stopped. Won’t be stopped. I will be the greatest.’’

Testimony is scheduled to resume Wednesday, with Shayanna Jenkins, Hernandez’s longtime fiancee and the mother of his child, slated to take the stand.

Travis Andersen can be reached at tandersen@globe.com. Fol-low him on Twitter @TAGlobe.