Light:”I can use my remaining life span to trade for the eyes… Just by looking at the person's face, I will be able to know his name… Not bad.. What a convenient eyes…”
Light:”Ryuk! About this trade… It's not within my consideration.”
Light decided not to trade half of his life span for the eyes as he treasures his life more than the eyes.
Ryuk told Light that it is alright if he doesn't want to trade. Ryuk only wants him to know that such trade exists. If not, the owner will complain if anything is not known to them in advance. Light is angry with Ryuk for telling him about such deal so late.
While Light is talking to Ryuk, something strikes his mind & he tells Ryuk that he knows of a way to find out the name of the man who tails him. One of the rules in the death note is that after writing the cause of death, the owner will have 6 min 40 secs to write the details of death
3 criminals died in a way which has never happened before. The 1st criminal draws a star in a circle on the wall before he dies.

The 2nd criminal writes a letter saying he's afraid of KIRA before he dies.

The 3rd criminal trys to escape from prison & runs to an employee toilet before he dies of heart attack.
All these cases are sent to L & L is thinking that KIRA may be testing on something or is it really the work of the individuals.
Light tested the death note but only 3 of his guinea pigs died in the way he wrote. The other 3 criminals manage to escape from death as the cause of death is not possible to happen. But, so long the condition of death is physically possible for the person whose name is written, it'll happen.
L is thinking what is KIRA up to if he really tested on the criminals. FBL will most probably have noticed any suspicious character when KIRA actions.

L notices something unusual from the suicide letter that the 2nd criminal has left.
L:”This… This is…”
えるしつているか
(L Do you know)

It's a saturday. Light has started his new plan. He made used of a runaway criminal & started to write something in the Death Note. After that he uses his mobile to call….
Yuri:”えつ!?ライト?おおはよう…”
(Eh!? Light? Mor.. Morning…”