When California Democrat Rep. Eric Swalwell sued his Republican colleague Mo Brooks to hold him accountable for his role in the events that sparked the Jan. 6 Capitol insurrection, he probably didn’t think he would have trouble finding him. The two work together at the Capitol, after all. Except Brooks has managed to duck all efforts to serve him with the papers for the lawsuit, which forced Swalwell to hire a private investigator to find him.

Brooks is the Alabama representative who spoke at the same rally as former President Donald Trump that immediately preceded the Jan. 6 riot. In a court filing on Wednesday, Swalwell’s attorneys told Federal Judge Amit Mehta they have been unable to locate Brooks and serve him with the lawsuit.

The judge gave Swalwell’s attorneys 60 days to find and serve Brooks, but the judge denied a request to get the US Marshals involved, “due to separation of powers concerns.”

Several media outlets have reportedly attempted to reach Brooks for comment about the lawsuit, but did not hear back. According to Swalwell’s attorneys, Brooks has used the strict security measures implemented after Jan. 6 to avoid being served. Neither he or his staff have returned calls or emails, and Swalwell’s private investigators have been hampered by tighter security measures. The Congressman’s lawyers detailed the difficulties in their court brief:

“Plaintiff had to engage the services of a private investigator to attempt to serve Brooks personally — a difficult feat under normal circumstances that has been complicated further in the wake of the January 6 insurrection at the Capitol that Defendants incited. Plaintiff’s investigator has spent many hours over many days in April and May at locations in multiple jurisdictions attempting to locate and serve Brooks, to no avail.”

Swalwell’s attorney Philip Andonian said on Wednesday’s “CNN’s Erin Burnett OutFront” that his team would continue to try to track down Brooks.

Swalwell’s suit names former President Trump, his son Donald Trump Jr., Trump’s personal lawyer Rudy Giuliani and Brooks. The lawsuit accuses the four of breaking Washington, DC, laws, including an anti-terrorism act, by inciting the riot, and that they aided and abetted violent rioters and inflicted emotional distress on members of Congress.

At the rally that day, Brooks exhorted the crowd by shouting, “Today is the day American patriots start taking down names and kicking ass.” He, like the others named, has denied any responsibility for the riot and dismissed Swalwell’s lawsuit as a “meritless ploy.”

The judge is expected to rule on whether the suit can proceed on July 8.