Who is Mahesh Nagar? It depends who you ask.

Mr. Nagar’s name appears on land office documents as the facilitator for land deals for India’s politically powerful Gandhi family.

Over four years, from 2009 to 2012, Mr. Nagar bought and sold tracts of land in Rajasthan on behalf of Robert Vadra, the 44-year-old husband of Priyanka Gandhi, whose brother, Rahul Gandhi, is spearheading the Congress party’s re-election efforts in national parliamentary elections that began April 7 and end next month.

Mr. Nagar has also bought land in Haryana on behalf of Mr. Gandhi in 2008.

In Rajasthan, the brokers who sold land to Mr. Nagar say they don’t have his contact information. In his home state of Haryana, next door to Delhi, officials at the land revenue office where he facilitated the purchase of land for Mr. Gandhi say they don’t have any information on Mr. Nagar either. Even his own brother, reached by phone, professes ignorance about where he is.

“Sorry, I don’t know his whereabouts,” said the brother, Lalit Nagar, a Congress party politician who ran and lost a bid for a seat in the Haryana state legislature in 2009 in Faridabad, a city near New Delhi.

But when a reporter showed up in Faridabad that same day, it was hard to find anyone who didn’t know Mahesh Nagar — and where to find him. A giant campaign poster in a marketplace near a local hospital featured Mr. Nagar, along with his brother, Lalit Nagar, and the leaders of the Congress party nationally — Mr. Gandhi and his mother, Congress party President Sonia Gandhi.

In an air-conditioned office in the same marketplace, Mr. Nagar, wearing a white shirt, lounged in a big leather chair, the walls decorated with pictures of Mr. Gandhi, Mrs. Gandhi and Mr. Vadra’s wife, Priyanka Gandhi.

Mr. Nagar and his brother live less than a kilometer away in a sprawling bungalow that bears both of their names on a sign out front.

Asked why he’s so elusive, Mr. Nagar smiles and asks, “Are you the reporter who called my brother this morning? I was there only when he was speaking to you.”

In the interview with the Wall Street Journal, he tried to distance himself from the Gandhi family, saying he’s never met them.

“Yes, I got some of the land registered for them,” he says. “But I don’t know the Gandhifamily directly.”

Land records show Mr. Nagar bought 6.4 acres of land for Mr. Gandhi in Haryana’s Hassanpur village in 2008. Then, in 2009, Mr. Nagar began showing up in the northwestern part of Rajasthan, buying nearly 2,000 acres of barren land on behalf of seven of Mr. Vadra’s companies over the next three years. He paid about 64,000,000 rupees, or about $1 million, for the land, according to a Wall Street Journal analysis of a summary of Mr. Vadra’s land deals that Kolayat land officials put together for a state investigation into his holdings.

Asked to explain Mr. Vadra’s land dealings, a spokesman said in an email that Mr. Vadra was a private citizen who had acquired real estate but “obtained no favor or benefit from anyone.” He had complied with the law and was unfairly being “subjected to a campaign to malign him for political reasons.”

In 2010 and 2011, the central and Rajasthan governments adopted tax incentives for the solar industry, which drew companies to the Bikaner area, which has among the highest irradiation levels in India. Land prices soared. Mr. Nagar, who bought Mr. Vadra’s land at an average price of 33,000 rupees, or $550, an acre, began selling the land less than three years later at more than six times that price, or an average per acre price of 220,000 rupees, about $3,700, according to the Journal’s review of the Kolayat land district office summary.

Local brokers and a local land official recall Mr. Nagar showing up frequently over the years in a black SUV, parking all day outside the Kolayat land office, and making deals in his vehicle. Brokers say they would enter the SUV to sign documents selling the land to Mr. Vadra’s companies.  Mr. Nagar would hand them payments in cash, the brokers say.

Asked how he came to be buying land for Gandhi family members, Mr. Nagar said somebody from Gurgaon, a growing suburb of Delhi, asked him to buy the land and gave him letters of authority to facilitate the land deals. He declined to identify the person.

Mr. Nagar said his buying for the Gandhi family is “all over now,” and that he’s no longer making purchases or sales for either Mr. Vadra or Mr. Gandhi. He said he doesn’t recall using a black SUV or paying in cash for land. Mr. Nagar declined to say what car he used in Rajasthan or how he did pay for the land. He said he got no special treatment by the land office.

Despite the Gandhi family photographs on the walls and poster of himself with Congress Party leadership outside his office, Mr. Nagar said in the interview that he didn’t have any political affiliation.

He said he was a farmer growing flowers, wheat and paddy, showing a reporter a business card bearing his name and academic credentials—a master’s degree in the arts and a law degree. However, the card was also imprinted with the symbol of the Congress Party, a hand.

Follow Geeta and India Real Time on Twitter @GOAnand and @WSJIndia.