could have known

0He said things that only 01del00a/02del00the murderer 01del00could/02del00could have known.0-

0 Only 01b00the02b00 murderer could know the details of the particular murder that he/she had committed 0-

0 For clarification, a more detailed sentence, which justifies the choice, would be: 02br
02br
01i00An investigator and I went to the home of the killer. He was toying with us. He 01b00said02b00 things that only someone who 01b00were02b00 the murderer 01b00could have known02b00.02i0-

0Sorry, MH. Why were instead of was? 02br
02br
00Thanks, Optilang. Can I generalize it using 'a' instead of 'the' in the sense that things that are commonly only known to a murderer?02br
00Thanks in advance.0-

0>Sorry, MH. Why were instead of was?02br
00To create a01b00 hypothetical02b00 context. I used 01b00were02b00 to make sure you read the sentence as such, and not as a fact. 0-

1i00 Can I generalize it using 'a' instead of 'the' in the sense that things that are commonly only known to a murderer?02i02br
00A murderer can say things that only he/she could know. 0-