The Supreme Court of India has ordered the Central Bureau of Investigation, a federal investigating agency, to probe a multi-million dollar government recruitment and admission scam in Madhya Pradesh, in a blow to the ruling Bharatiya Janata Party (BJP) which runs the central state.
The probe will also examine the deaths of over two dozen witnesses and accused persons in what opponents of the ruling party say points to a massive cover-up.
Investigations have been carried out at state level since the case came to light in 2013.
It found that from 2007, thousands of job and admission seekers paid bribes to manipulate results for state-level government jobs and places in institutes of education. Some applicants got others to sit their entrance examinations, while others cheated during the exams.
The investigators also said the deaths are not connected.
Almost 2,000 people, including students, bureaucrats, businessmen and politicians - including a former state education minister - have been arrested in connection with the case.
Madhya Pradesh chief minister Shivraj Singh Chouhan, a popular BJP politician, has been facing calls from the opposition to resign over the issue.
He said he welcomed the court order that takes the probe away from the state authorities.
"This case has been like a weight on my chest. It has been a trial by fire. There was a problem, we got it investigated and those accused are in jail and I have cleaned the full system. Now, the truth behind the deaths should emerge," he said .
The governor of Madhya Pradesh, Mr Ram Naresh Yadav, is also in trouble with the Supreme Court, which is currently hearing a plea seeking his sacking for alleged involvement in the scandal.
India has seen a string of scams in recent times, from corruption in allocation of coal blocks to the sale of telecom spectrum licences.
But the exam scam - known as Vyapam, the Hindi acronym for the professional examination board - stands out because of the number of fatalities involved.
Last week, television reporter Akshay Singh, 38, died while interviewing the family of a dead girl who had been linked to the scam. Reports said he was foaming at the mouth when he was rushed to a hospital. Doctors have so far not found any proof of foul play.
Two days later, Dr Arun Sharma, 64, a dean of a medical college who had been helping investigators, was found dead in a Delhi hotel. His death is also being investigated, but preliminary tests have also not found proof of foul play.
On June 28, veterinarian Narendra Singh Tomar, 29, who was in jail in connection to the case, died after complaining of chest pains.
While some unofficial estimates put the number of deaths at more than 40, other deaths have occurred due to suicide, drowning, road accidents and heart attacks.
The opposition Congress party called the federal probe the "beginning of justice" even as it demanded Mr Chouhan's resignation.
"The BJP can no longer say that corruption happens only under Congress rule," said political analyst Sudhir Panwar.
"Prime Minister Narendra Modi promised clean governance and he can't explain it away by saying this is happening in a state."