RALEIGH, N.C. (CN) – Formerly secret files of a deceased mapmaker were displayed for the first time publicly in a Raleigh court Friday, concluding week one of North Carolina’s lengthy trial to determine if Republicans unfairly gerrymandered state political districts in their party’s favor.

Expert witness Christopher Cooper testified Friday and Thursday evening on behalf of the North Carolina Democratic Party, an advocacy group called Common Cause and more than 30 voters who brought a partisan gerrymandering-related case against North Carolina lawmakers.

When asked on Thursday why he decided to testify, Cooper said that it would help him address a concerning puzzle to him personally, and that, “It seems like our General Assembly is out of step in a lot of ways from other elected offices in North Carolina.”

Stanton Jones, counsel for the groups who brought the case challenging district maps adopted by state lawmakers in 2017, said on Monday there is no possible way for Democrats to achieve a majority in state elections due to heavily gerrymandered voting districts that were drawn by Thomas Hofeller.

Hofeller, whose estranged daughter turned over his district mapping files to Common Cause, died last year.

He drew the maps, which were adopted by the North Carolina General Assembly in 2017, after the state was ordered to replace the racially gerrymandered 2011 maps that Hofeller also created.

Jowei Chen was an expert witness for the plaintiffs during Wednesday’s hearing.

Chen testified he found data in screenshots from Hofeller’s computer that showed the mapmaker most likely used both partisan and racial data to decide where North Carolina residents can vote.

Hofeller’s district map was identical to the one approved by the General Assembly to guide 2018 elections and beyond.

Chen said he found Hofeller manually entered “%18_ap_blk” into the mapping software’s formula box of nearly every draft that Chen said he analyzed. This formula, the political scientist explained on Tuesday, was used to calculate and track how many African American citizens were of voting age in each district.

Though racial gerrymandering was the focus of many previous lawsuits against the state, it is the focus on partisan gerrymandering that sets this specific case apart for the rest.

Phillip Strach, chief counsel for state Republican legislators, said it was the Democratic Party’s own fault for not recruiting electable candidates and that the court should not have a say in determining the matter at hand— a districting decision to be made by the state Legislature.

Whether North Carolina’s voting population was unconstitutionally cracked and packed — a term used to describe the gerrymandering method of intentionally splitting and combining certain constituents into different voting districts to favor one party — is a decision left to the three-judge-panel in the state’s capital.

After the U.S. Supreme Court declined in June to take up the issue, the plaintiffs brought the case to the Superior Court in Raleigh. They say 95 of the 170 state House and Senate districts drawn two years ago violate the North Carolina Constitution’s free speech and association protections.

Cooper on Friday concluded in court that Hofeller took political leanings into account when drawing North Carolina’s political maps.