(CNN) — House Republicans are taking their next official steps in their impeachment inquiry of President Joe Biden by preparing a hearing and subpoenas to members of the Biden family, as well as scheduling the first hearing in the investigation for Sept. 28.

A committee spokesperson told CNN that the hearing will focus on the constitutional and legal questions Republicans are raising about Biden.

While the witnesses are still being finalized, House Oversight Chairman James Comer told CNN he plans to have a financial expert speak to the bank records he has uncovered pertaining to the Biden family’s business dealings and a constitutional expert to discuss why an impeachment inquiry is warranted.

“It’s an informative hearing where we’re going to have some experts in different areas of the law that can answer questions pertaining to specific crimes, as well as to educate and inform exactly what an impeachment inquiry is, and why you do an impeachment inquiry,” Comer, a Republican from Kentucky, told CNN.

The Oversight panel is also poised to issue its first subpoenas to the president’s son and brother, Hunter and James Biden, as early as this week, according to the spokesperson. The subpoenas are the first direct outreach to members of the Biden family and are expected to be for their personal and business records.

Republicans have made Hunter Biden’s business dealings a central component of their impeachment inquiry, but there is no public evidence to date that the president personally received any money.

House Speaker Kevin McCarthy unilaterally authorized the impeachment inquiry last week and tasked House Oversight, Judiciary, and Ways and Means committees to lead the effort. The framework for the inquiry is still being worked out among the key players, a source familiar tells CNN.

“We are still finalizing with the Ways and Means Committee, Judiciary Committee and the Speaker’s Office all of the details of the impeachment inquiry. Once all of the I’s are dotted and T’s are crossed, I expect to issue a subpoena for Hunter and James Bidens’ personal bank records,” Comer said.

Comer has previously issued subpoenas to six banks for information regarding specific Biden family business associates to investigate the money trail behind the Biden family’s foreign business dealings.

As House Republicans take definitive steps in their inquiry, key questions remain. There are a number of GOP members who do not support the inquiry, citing the lack of direct evidence against the president. Members disagree over how long the inquiry should last – some want to move quickly but others say they need time to get the reluctant lawmakers on board. And ultimately, the question of whether the inquiry will lead to bringing formal articles of impeachment against Biden still hangs in the balance.