Thomas C. Maslin, with wife Abigail and son, Jack. (Courtesy Abigail Maslin)

Thomas C. Maslin will never fully recover from the beating on Capitol Hill that left him in a coma for six days, his lead surgeon testified in D.C. Superior Court on Wednesday.

Neurosurgeon Christopher Kalhorn testified in the robbery and assault trial of Tommy Branch, 22, who is charged in the Aug. 18 attack in a tiny park near Eastern Market. Branch and two friends allegedly robbed Maslin of his iPhone, credit cards and keys as Maslin was walking home about 1 a.m. after having beers with some friends following a Nationals baseball game.

Sunny Kuti, 18, of Southeast Washington has requested a separate trial. Michael Moore, 19, of Landover pleaded guilty in the case and has agreed to testify against Branch.

On the first day of Branch’s trial, Kalhorn testified that Maslin, 30, underwent several brain and skull surgeries as a result of blunt-force trauma that fractured and shattered his skull and caused severe brain bleeding. Jurors were shown a photo of Maslin in his hospital bed, his left eye swollen and blackened.

Prosecutors said Branch struck Maslin with an aluminum baseball bat. Branch, who is charged with 13 counts in the case, carried the bat in his car and called it his “Barry Bonds,” according to a law enforcement source familiar with the case.

The robbery was Branch’s idea, Assistant U.S. Attorney Thomas Swanton told jurors in Judge Robert Richter’s courtroom. Kuti agreed to the plan, he said, but was concerned about getting blood on his new shoes.

Kuti, the prosecutor said, carried a black BB gun that didn’t work.

Branch's attorney, Dorsey Jones, argued that it was Moore who struck Maslin with the bat. Jones said Moore was trying to deflect the assault charge onto Branch after pleading guilty to other offenses.

Maslin was found unconscious on the front porch of a Capitol Hill rowhouse about 8 a.m.

Within minutes of the attack, according to court records, the suspects climbed into Branch’s silver Hyundai Sonata and drove to an Exxon station in Southeast, where Branch is alleged to have tried unsuccessfully to use Maslin’s credit card.

Branch, Kuti and Moore were arrested after a second attack a few hours later. According to court records, the three drove to Adams Morgan, where they allegedly robbed two men of their wallets and cellphones about 3 a.m.

One victim in that attack told authorities that an assailant ordered him to “give him everything.” He was knocked down by a second who brandished a gun, according to court records.

Outside the courtroom, Branch’s mother, who was scheduled to testify against her son, became hysterical and began sobbing before she was called to the witness stand. Courthouse security and health officials spent about 10 minutes trying to calm her down before she was removed from the courthouse. Prosecutors had said she would testify that she destroyed the bat after her son’s car was recovered.

It was unclear whether prosecutors planned to call Maslin or his wife, Abigail, to testify.

Under sentencing guidelines, Branch could face a maximum of about 30 years in prison if convicted on all counts. The trial is expected to continue through next week.