Vinit Gupta, is an officer at Coal India limited and often he is given duty to work as an election officer during election times. He gave below comments in quora to support his voice for ruling BJP ( Bharatiya Janta Party) and clearly stated that BJP has not won by fraud using EVM else it could have won in all the states, why only Uttar Pradesh–

Being an employee in a PSU, I had been assigned duties as a polling officer a couple of times (2013 MP LA election and 2014 LS election). There is a fixed procedure for polling with EVMs, so that every candidate is satisfied with the fairness in polling and the EVM.

Generally election starts at 8AM(somewhere 7AM also). All the polling officers and presiding officer have to present 1hr prior to the polling time. Agents of different parties also are present there. In their presence the designated officers have to conduct a mock polling and show all the agents that the EVM is working fine(like it is registering the votes or not, registering for the right candidate or not, it's showing correct counting or not, etc. ). Then again in the presence of all the agents the designated officer locks and seals the EVM and countersign on it alongwith all the agents, so that nobody can make any alteration in the machine after it has been locked. After the completion of poll the EVM is sealed off completely and again with the sign of agents. Then it is submitted to the collectorate office. At the time of counting, again the EVM is opened in front of the agents of candidates. Hence there is no chance of a victory of any party by doing fraud in the EVM.

So, with my experience all these accusations are baseless and if BJP has some other way to tamper with the EVMs why hasn't it done that in other states?

We also did some fact check on what Mr Vinit mentioned in his blog on quora and found it to be correct. The election commission describes below duties to the polling agents-

MAIN DUTIES OF POLLING AGENTS

The  main  duty  of  the  polling  agents is  to  see  that  the  interests  of  the candidates who  have  appointed  them  are  safeguarded  at  the  polling  stations.

Their other duties are:

(a) To take part in the mock poll and satisfy themselves that the EVM is in proper working order,

(b) To  help  the  Presiding  Officer  to  detect  and  prevent  impersonation  of voters by challenging persons whose identity as real elector is doubtful,

(c) To  help  in  having  the  voting  machine  properly  secured  and  sealed according to the rules before, during and after the close of poll,

(d ) To  see  that  all  election  records  relating  to  the  poll  are  secured  and sealed properly after the close of poll as required by law, and

(e) To see that the serial numbers of Control Unit, the Ballot Unit and printer with drop box of the EVM being used in the polling station are in conformity with the details provided by the Returning Officer.

To read more, refer the pdf issued by Election commission of India - http://eci.nic.in/eci_main/ElectoralLaws/HandBooks/Polling%20agents_24022014.pdf

So, if Kejriwal and Mayawati are blaming BJP for the misconduct happening due to usage of EVM, then they should first question their polling agents.