The loophole that allows them to take office is that they have not been convicted — in part because the Indian legal system has a huge backlog of an estimated 30 million cases and trials often last decades. When asked about the charges against them, they invariably accuse a political rival of framing them.
Since such rivalries often lead to false accusations, the main political parties say it would be unfair to bar people from contesting elections unless they have been convicted by court.
Under existing laws, only those who have been sentenced to prison for two years or more can be barred from elections.
Members of Parliament with criminal backgrounds is not a new phenomenon in India, but despite Modi's campaign vow in 2014 to clean up corruption and the influence of money in politics, the problem appears to be only worsening.
In the 2004 national election, the percentage of candidates with pending criminal cases was 24%, which rose to 33% in 2009, 34% in 2014 and 43% this year, said Shahabuddin Y. Quraishi, a former chief election commissioner.
The Association of Democratic Reforms found that 116 of the 303 lawmakers from Modi's Bharatiya Janata Party elected last month face criminal charges, including one for alleged terrorism.
Pragya Singh Thakur, who won a seat from Bhopal in central India, is awaiting trial in connection with a 2008 explosion in Malegaon in western India that killed seven people.
Twenty-nine of the opposition Congress party's 52 lawmakers face serious charges.
"This trend has been growing in India, leaving no political party untouched. We need to educate voters not to elect these people," said Jagdeep S. Chhokar, ADR's founder.
"What the Indian state has been unable to provide, strongmen promise to deliver to people in their area of influence, using gun and money power," said Lennin Rasghuvanshi, a coordinator with the People's Union for Civil Liberties.
Starting in the 1960s and '70s, some Indian politicians began turning to the criminal underworld for cash to win votes.
"In due course, the criminals started thinking that these politicians were winning because of their money or crimes so why shouldn't they become lawmakers themselves? If they are people running from the police, they know that when they became lawmakers, the same police will protect them," Quraishi said.
In Uttar Pradesh state in northern Indian, former mafia don Mukhtar Ansari has been elected to the state assembly five times despite more than 40 criminal cases pending against him, including murder.
Another don-turned-politician, Hari Shankar Tiwari, also of Uttar Pradesh, has been a member of the legislative assembly for 23 years, even winning an election while being detained on murder charges.
During the campaign, Election Commission officials and government agencies seized mountains of cash, alcohol, gold and silver, saris and expensive watches in the offices of political parties that were intended as gifts in exchange for votes.
The total value of the seized goods was $500 million, including $120 million in cash — nearly three times what was found in the 2014 general election, according to the Election Commission.
Analysts say that political parties seem to prize electability over ethics.
"They think that people with criminal backgrounds have more chances to win because of their money and muscle power," Qureshi said.
In the days of paper ballots before electronic voting machines were introduced, gangs would use brute force to take over polling stations to rig the vote.
One reason for the increasing number of criminal suspects going into politics is the sheer cost of elections. In the general election that concluded in May, political parties and candidates are estimated to have spent about $8.65 billion. That's double the amount in the 2014 election, according to a report by the Center for Media Studies in New Delhi.
The report said the Bharatiya Janata Party was the biggest spender, accounting for about 45% of the total. The Congress party accounted for between 15% and 20%.
Analysts say a key cause of corruption is the way political parties are funded in India. Parties are permitted to receive foreign funds, any company can donate any amount of money to any political party, and any individual, group or company can donate money anonymously through electoral bonds.
Donors do not need to disclose the party they have donated to, nor does the party have to reveal the source of its money.
Quraishi is calling for more transparency in campaign funding as well as a cap on election spending.
"The people want transparency, the donor wants secrecy. Whose wish should prevail?" he said.