What does “suspect” mean?
A suspect is someone who maybe did something bad.
An example
The food is gone from the picnic basket. The dog, the cat and the bird are suspects.
Where do I hear it?
The word “suspect” is one of the three words of Part 2: Why Is Catarina So Nervous?, a short mystery in easy English (level A2). Hear it in the video, from 0:37.