Quoting the probe report, he said there was a dispute between a train guard Shariful Islam and TTE Shafiqul Islam as the former instigated the three passengers to file allegation against the latter one.
The complainant Imrul Kayes admitted the matter to the probe body.
The three-member investigation committee headed by Pakshi divisional railway assistant transport officer (ATO) Sajidul Islam submitted the report to the office of Shahidul Islam at around 11:20am on Monday.
Sajidul told the journalists that nine people, including complainant, TTE, were interrogated. A 40-page probe report with recommendations has been submitted.
Shahidul Islam said guard Shariful Islam has been served a notice. Necessary measures would be taken against him after the reply is received.
On 5 May, Shafiqul fined three relatives of railway minister Nurul Islam Sujan for travelling without ticket. Soon after the incident, he was suspended on allegation of misbehaving with the trio.
The incident came to the fore and took dramatic turns in the following days. The minister initially denied the passengers to be his relatives, but later was compelled to backtrack and admit them.
In the face of widespread criticism, the authorities revoked the suspension order of TTE Shafiqul and served a show-cause notice to the officer who issued the suspension order.