The factory offices were robbed during the night.
There was no sign of a break in.
Of the four safes in the office, only the one containing cash was opened. The others show no sign of being opened.
Some members of staff went missing the next day.	
The train was derailed on straight track in broad daylight.
On inspection there was nothing wrong with the train 
but some parts of the track were missing.	
The factory burned down over the weekend.
It had recently passed a fire safety inspection.
The owner had recently increased the insurance. 
The owner was having financial problems.
Some traces of petrol were found during the investigation.
	
The plane crashed into a mountain.
The pilots had never flown that route before.
Just before the crash, the pilots radioed to say everything was fine.	

The factory offices were robbed during the night.
There was no sign of a break in.
Of the four safes in the office, only the one containing cash was opened. The others show no sign of being opened.
Some members of staff went missing the next day.	
The train was derailed on straight track in broad daylight.
On inspection there was nothing wrong with the train 
but some parts of the track were missing.	
The factory burned down over the weekend.
It had recently passed a fire safety inspection.
The owner had recently increased the insurance. 
The owner was having financial problems.
Some traces of petrol were found during the investigation.
	
The plane crashed into a mountain.
The pilots had never flown that route before.
Just before the crash, the pilots radioed to say everything was fine.	
Answers	

Robbery
It appears / seems to be an inside job. 
(Present tense – use if the story is current.)
It appears / seems to have been an inside job. 
(Past form – use if it happened some time ago.)

Adding 'would' makes the statement slightly less certain.
It would appear / seem to be an inside job.
It would appear / seem to have been an inside job. 

Train derailment
It appears /seems to be sabotage.
It appears / seems to have been sabotage.

It would appear / seem to be sabotage.
It would appear / seem to have been sabotage.

Factory fire
It appears / seems to be an insurance fraud.
It appears / seems to have been an insurance fraud.

It would appear / seem to be an insurance fraud.
It would appear / seem to have been an insurance fraud.

Plane crash
The pilots appear / seem to have got lost.
It appears / seems that the pilots got lost.

The pilots would appear / seem to have got lost.
It would appear / seem that the pilots got lost.