A graduate student at the University of North Carolina at Chapel Hill accused of a fatal shooting that sparked a campus-wide lockdown and national headlines is not mentally fit to stand trial, defense attorneys argued in court Tuesday following a doctor's evaluation.

Tailei Qi, 34, was arrested and charged with first-degree murder and having a gun on an educational property after the fatal shooting on campus last month of Zijie Yan, an associate professor in the department of applied physical sciences.

The Aug. 28 shooting sent the college into a roughly three-hour lockdown. Videos posted on social media showed a heavy police presence, with dozens of officers and a helicopter overhead as people fled buildings, some even climbing out of windows. Classes were cancelled at UNC Chapel Hill just a week into the semester.

Qi addressed the court Tuesday in a lengthy statement, in which he criticized the mental-capacity evaluation conducted by a doctor at the request of his attorneys, WRAL reported. Qi also expressed dissatisfaction with his attorneys, saying that claims of mental health concerns were a way to “bypass” that concern.

The judge has ordered Qi undergo a second mental evaluation to determine whether the trial can proceed. 

Qi is listed in the department of applied physical sciences on the university's website, accessed by USA TODAY through internet archives. Yan, the faculty member killed in the shooting, is listed as Qi's adviser. The two also co-authored research papers.

Law enforcement officials have not publicly announced a motive for the shooting. The Orange County district attorney confirmed on Tuesday that the gun had still not been found, ABC 11 reported.

Qi's next court appearance is tentatively scheduled for Nov. 14.