Attendance Timing For Office Duty

Dear seniors
Pl guide one employee is on duty since 8.30 to 4.20pm on a day and when he enters in the office premises time of in is 4.20pm but he complains that suppose anything goes wrong with his/her life during that pariod from 8.30 to 4.20 then company may refuse to take responsibilty as his/her in time was at 4.20pm though he was on office duty.
He/she is sample asst of my company and gone for site complain handling from 8.30 and came at 4.20.
Am I right taking in time as 4.20pm in attendance with remarks Office duty,or
He is right that the in time should be from 8.30am ..........
Off time is 10.00 am to 7.30 pm.
Kindly suggest
thnx
tarun

thnx
this is nothing an argument why i should not put his in time 8.30 as he was on office work but my point is as he entered at 4.20 pm in office premises though he was on office duty but that should be timing at 4.20pm with office duty.......
so who is right me or the staff member...
thnx
tarun