ROCKVILLE — The trial for the man accused of the midmorning rape of a woman on a Red Line train concluded Friday evening after four days of testimony that included an appearance from the accused’s mother.

A full day of testimony from DNA experts discussing blood and semen preceded closing arguments in which the attorney for John Hicks, 41, of D.C. said police arrested the wrong man. The case was heard in Montgomery County Circuit Court.

Defense attorney Sam Sandler said a bad investigation and bad identification led to Hicks’ arrest. The attorney contended that Hicks doesn’t match the description that the victim gave police of the man who assaulted her on a train traveling between the Fort Totten and Glenmont stations.

The attack happened just before 10 a.m. on April 12. She was on the train because she had missed her bus.

Hicks was picked up just a few hours later, Sandler said, because detectives decided who they wanted to arrest — disregarding disparities between the suspect description and Hick’s height, hair, facial hair and pants color.

The victim testified in court that she is 100 percent certain that Hicks is the man who attacked her.

The prosecution’s case included Metro surveillance video that was shown to Hicks’ mother, who testified the person seen entering and exiting trains before and after the attack is her son.

Evidence presented by Assistant State’s Attorney Elizabeth Haynos included a tissue with Hicks’ semen and the victim’s blood on it and items she said detectives found in Hicks’ home: a knife with the victim’s blood on it, a fare card placing Hicks’ in Metro during the time in question and clothes matching those shown in the surveillance video.

During the attack, the victim reached for the knife she was being threatened with and cut her middle finger. Charges against Hicks include first-degree rape. A conviction on that charge can lead to a sentence of up to life in prison.

Jury deliberations will resume Tuesday.