Can someone suggest if the ball can be spun by a fast bowler?
What should be the crucial points to look out for?

Fast bowlers can spin the ball. But for doing this they usually reduce the speed at which they are bowling. The two common slower deliveries that fast bowlers bowl are off-cutters and leg-cutters. Off-cutters usually spin into a right handed batsman (like harbhajan, muralitharan) while leg-cutters spin away from a right handed batsman (shane warne style ).
But fast bowlers don't usually generate enough spin to actually make you see the ball move after pitching. This is because an average spinner bowls at around 80 kmph. Whereas a pacer bowls at around 130 kmph (slower deliveries would be at 100-110 kmph). You would probably break your index finger r cut it really badly trying to spin at that speed.

Fast bowlers usually use these deliveries to slow the speed of the ball without slowing hand speed so as to deceive the batsman. And, to generate spin, he would have to really reduce his speed which will not be possible without reducing his hand speed and the delivery will become easy to pick for the batsman.