Robert Vadra, Congress president Rahul Gandhi's brother-in-law, was interrogated for nine hours on Tuesday by the Enforcement Directorate in connection with an alleged land scam in Rajasthan's Bikaner district.
The questioning will resume at 10.30 am Wednesday, his lawyers said.
His mother Maureen was also questioned for some time, but Vadra remained at the ED's zonal office till about 8.30 pm, except for a lunch break during which he was allowed to leave the premises for an hour.
All India Congress Committee general secretary Priyanka Gandhi Vadra dropped Vadra and his mother off at the ED office, taking time off from her four-day Uttar Pradesh trip in a show of solidarity with her husband.
Congress workers shouted slogans when Vadra arrived for the questioning and when he left for his hotel at night.
"The interrogation lasted for nearly nine hours. He has given answers to the questions from the ED officers. He will once again appear before the ED zonal office in Jaipur at 10.30 am," Vadra's lawyer Suman Jyoti Khaitan told reporters.
Vadra's lawyers said his mother has not been called for questioning as she is not keeping well.
She has, however, assured full cooperation in the probe, they said.
On Facebook, Vadra accused the Narendra Modi government of being vindictive ahead of the Lok Sabha elections, and putting his mother through harassment.
This was Vadra's first appearance before the ED in Jaipur in connection with charges of money laundering through land deals made by a company linked to him.
Vadra was asked by the Rajasthan high court to cooperate with the agency.
His Jaipur appearance follows soon after he faced ED questioning for three days in Delhi on a different set of charges relating to property allegedly purchased in London.
Vadra is also facing accusations of irregular land deals in Haryana's Gurugram district.
Vadra and his mother reached the ED's zonal office at Bhawani Singh Road, amid tight security.
Near the ED office, some Congress workers shouted slogans in support of Priyanka Gandhi, and also repeated the slogan given by her brother Rahul Gandhi, calling Modi a 'thief'.
'Chowkidar chor hai,' they shouted.
Several hoardings were put up nearby showing pictures of Priyanka Gandhi and Robert Vadra, and saying that people wanted Rahul Gandhi and Priyanka Gandhi to come to power this time.
"Jan Jan ki hai yehi pukar, Rahul ji-Priyanka ji abki baar,” the banners said.
Rajasthan Congress vice president Archana Sharma, however, claimed she was not aware of such posters.
"The party has not put up any such hoardings," she said.
Before the questioning started, Vadra accused the government of harassing his elderly mother by putting her through it.
"As I always have adhered to rules and overall being a disciplined person, I have the ability to sustain any amount of hours of questioning and having nothing to hide, I will answer every question with respect and dignity. This too shall pass and will make me stronger," he said.
"So here we are my 75-year-old mother and me in Jaipur to depose in front of the Enforcement Directorate.
"Not understanding the lows of this vindictive government to be harassing a senior citizen, who the world knows has lost her daughter in a car crash, her ailing son to diabetes, and her husband as well," he posted.
In the Bikaner case, the agency had summoned Vadra thrice but he failed to appear before it.
The Rajasthan high court asked him and his mother to cooperate with the agency after they approached it, seeking directions that no coercive action is taken against them by the ED.
The ED had registered a case in connection with the deal in 2015, taking cognisance of a clutch of first information reports and chargesheets filed by the Rajasthan police after the Bikaner tehsildar complained about alleged forgery in land allotment.
It is understood that the agency wanted to question him on the operations of Skylight Hospitality Private Limited, allegedly linked to him, which purchased land in the area.
It also wanted to confront Vadra with the statements of those said to be linked to him.