Answer the questions at the end based on the text.

Boston (CNN)It was 9:35 on a slow Thursday night in April 2013 and Massachusetts Institute of Technology Police Chief John DiFava was about to call it quits. On his way out, he saw one of his rookie swing-shift officers, Sean Collier, sitting in his cruiser. He stopped to say goodnight. 

"I chatted with him for a few minutes. I told him to be safe and I left," the chief told a crowded courtroom on Wednesday. He estimated the conversation lasted three, maybe four minutes. 

"Did you ever see Sean Collier alive again after that?" Assistant U.S. Attorney William Weinreb asked. 

"I did not." 

Less than an hour later, Collier lay bleeding in his patrol car after being ambushed and shot in the head. His car door was open, and his foot was lodged between the gas and brake pedals. 

DiFava and other officers, assisted by surveillance videos, 911 callers and a lone bicyclist who happened to be passing by, recounted Collier's last moments in the death penalty trial of admitted Boston Marathon bomber Dzhokhar Tsarnaev. 

The bicyclist, MIT mathematics Ph.D. candidate Nathan Harman, pointed to Tsarnaev in court and identified him as the man with "a big nose," who he saw leaning into Collier's squad car. He said Tsarnaev appeared to be alone. 

Tsarnaev, who was 19 at the time, does not dispute that he was present when Collier was killed on the evening of April 18, nor does he deny that he participated in the bombings three days earlier that killed three people and hurt more than 240 others. 

1. What time was it?
2. What day of the week?
3. Night or day?
4. Who is Assistant U.S. Attorney
5. Who did he talk about
6. What month was it?
7. What year?
8. What city?
9. Was John DiFava a Police Chief
10. Where?
11. Who is Sean Collier
12. Is he dead?
13. Who is Nathan Harman
14. Does he bicycle?
15. Who is Dzhokhar Tsarnaev?
16. How many people did he injure?
17. How many people did he kill?
18. What was the date of that?
19. How old was the bomber?
20. What was the date when Collier died?

Numbered answers:
1. 9:35
2. Thursday
3. night
4. William Weinreb
5. Sean Collier
6. April
7. 2013
8. Boston
9. yes
10. Massachusetts Institute of Technology
11. a police office
12. yes
13. an MIT mathematics Ph.D. candidate
14. yes
15. the Boston Marathon bomber
16. more than 240
17. three
18. April 15
19. 19
20. April 2013