Réponse :
1)
Underline in blue "Shauna" in the text
Underline in red "April [...] getting the post"
"Alyssa [...] playing with the children"
"Reggie [...] preparing the meal"
"Mark [...} planting flowers"
Underline in green "The police"
Underline in black "Sunday morning"
2)
Highlight "when she found the body"
"when Reggie, the cook, asked her to come"
'when there was a shot"
"when he heard April scream"
1st picture = Reggie
2nd picture = April
3rd picture = Mark
4th picture = Alyssa
3)
I guess the crime weapon is a knife because we can see on the 2nd picture that Shauna was killed by a knife.
4)
I guess the murderer is Reggie, he killed Shauna. The police knew they had to arrest him because he said he heard a shot but Shauna was killed by a knife. So he lied.
Voilà j'ai fait du mieux que je pouvais, j'espère que ça t'aidera.