investigates

As a noun scientist

is one whose activities make use of the scientific method to answer questions regarding the measurable universe a scientist may be involved in original research, or make use of the results of the research of others.

As a verb investigates is

(investigate).

As verbs the difference between predict and investigates

is that predict is to make a prediction: to forecast, foretell, or estimate a future event on the basis of knowledge and reasoning; to prophesy a future event on the basis of mystical knowledge or power while investigates is third-person singular of investigate.

As a noun predict

is a prediction.

As verbs the difference between investigates and investigated

is that investigates is (investigate) while investigated is (investigate).