Previously, Deuba served as Nepal's prime minister four times from June 2017-February 2018, June 2004-February 2005, July 2001-October 2002 and September 1995-March 1997.
The JSP has made an electoral alliance with main opposition Communist Party of Nepal-Unified Marxist Leninist headed by K P Sharma Oli.
The two sides also inked four pacts to expand cooperation in areas of railways and energy.
The MEA said at Lumbini, the prime minister will visit the sacred Mayadevi temple to offer prayers.
Nepalese Prime Minister Sher Bahadur Deuba, however, did not give a timeframe for the completition of the investigations.
The government wanted 'secret talks with Maoists' as 'whenever they have been held openly, they have failed,' the prime minister said.
The assurance was contained in a joint statement issued at the end of the five-day visit of Nepalese Prime Minister Sher Bahadur Deuba to India.\n\n\n\n
'Indiscriminate killing, abduction, extortion and torture can't be acceptable ways to bring about political change,' Deuba told the second World Summit on Buddhism at Lumbini.
The 76-year-old Nepali Congress president, who has served as the prime minister for a record fifth term, defeated his challenger party general secretary Gagan Kumar Thapa by 39 votes, officials said.
Modi, who is in the Himalayan nation at the invitation of Deuba, is paying a day-long visit to Lumbini on the occasion of Buddha Purnima.
Madhav, the chairman of the Communist Party of Nepal-Unified Socialist, was present in a special court to present his arguments relating to the land misappropriation case.
Oli stepped down shortly after hundreds of demonstrators entered his office shouting anti-government slogans.
Modi and Deuba discussed ways to strengthen ongoing cooperation and develop new areas in the multifaceted bilateral partnership.
The protesters shouted slogans such as KP Chor, Desh Chhod (K P Sharma Oli is a thief, quit the country), "Take action against corrupt leaders".
India also offered to help Nepal deal with the Maoist problem.
Deuba was elected as the 40th prime minister on June 6 with the support from Communist Party of Nepal-Maoist Centre, which is now a part of Left alliance and opting for merger with Communist Party of Nepal-Unified Marxist-Leninist.
The Nepal government signed a $215.96 million soft loan agreement with China in March 2016 for the construction of the airport in this tourist hub.
Nepal's Prime Minister Sher Bahadur Deuba on Monday inaugurated the country's second international airport built by China that will help connect Lumbini, the birthplace of Lord Buddha and a major tourist and pilgrimage destination, to Buddhist circuits in South Asia as well as to the rest of the world.
The pact was to run the government on a rotational basis until elections to the parliament are held.
He recalled PM Modi's message at the United Nations and hailed India's mission "to save the planet from conflict and violence" through the principles of Buddhism.
Here are the highlights of Modi's second day in Nepal.
One fact is irrefutable: Nepal's recent political history tells us that the route to a return of monarchy cannot go through India despite friends in high places, asserts Aditi Phadnis.
Much to the surprise of Beijing, Nepal's Parliament on Sunday ratified the contentious US-funded $500 million Millennium Challenge Corporation compact along with an interpretive declaration a day ahead of the February 28 deadline set by Washington.
Once completed, the Centre will be a world-class facility welcoming pilgrims and tourists from all over the world to enjoy the essence of spiritual aspects of Buddhism, projecting India's growing soft power.
In his condolence message, Israeli Prime Minister Lapid said that the thoughts and prayers of all Israelis are with the people of India following yesterday's devastating bridge collapse in Gujarat.
Nepal witnessed political turbulence in 2022 that dramatically turned rivals into allies and throned former guerrilla leader Pushpa Kamal Dahal 'Prachanda' as the prime minister for a third time, as Kathmandu made efforts to balance ties with immediate neighbours India and China with high-profile talks and visits.
Now it is confirmed that all 22 people, including four Indian nationals and three crew members, have been killed in the tragedy.
Whether it is Sri Lanka, Maldives, or Nepal, quietly but steadily, India has been reclaiming some of the ground it had lost to China, observes Aditi Phadnis.
Rescuers on Monday recovered 20 bodies from the wreckage site of the Tara Air plane that crashed in Nepal's mountainous Mustang district on Sunday with 22 people on board, including four Indians, minutes after taking off from the tourist city of Pokhara, officials said.
India last month reacted angrily to Nepal showing the three areas as Nepalese territory in the new map and cautioned the country that saying such "artificial enlargement" of territorial claims will not be acceptable to it. India has been maintaining that these three areas belong to it.
'By treating Nepali politicians as shabby buffoons to be pampered one day and collared another day, India badly exposed itself.' 'A belief got entrenched in the Nepalese mind that we are a dangerous neighbour,' observes Ambassador M K Bhadrakumar.