This could've been easily detected with a diligent inspection, and it could've been argued the owners were aware of it.  

Find your inner detective and go searching for answers.No, make that thirsty, like you're trying to find the solution to a rare disease and this overdone is your last hope.What should you do?  

The tenant's father was a detective in another muni and known to the local police.  

So the odds of them avoiding you and never showing, paying or contacting you are probably higher than them showing up at your door.Then, of course, try to screen tenants more closely, and this may hint at another issue with the pm if they got you tenants with problems that could have been detected with a standard screening procedure...

Can anyone please recommend a good and reasonable electrician whose help I can take to detect the problem and resolve it? 

He appeared to be a bumbling detective, disorganized and absent minded, however this is the farthest thing from the truth.

Unless you want to call them, then you can do some detective work via Google.

Test your rehab/renov detection skill (bring seller disclosure)6.

Test your rehab/renov detection skill (bring seller disclosure)7.

You have done some great detective work thus far.