"aid in" with the noun

I often find it confusing when to use "aid in" instead of "aid."

A similar question has been posted before, but this thread mainly addresses when a gerund, or participle is the object of the preposition "in."

Could anyone explain why "aid in" is used in the following examples? What would be the difference if it said "aid" instead?

• Interpol is sending a response team to the French city of Nice to help identify victims and aid in the investigation into the truck attack that left at least 84 people dead.(http://www.nytimes.com/aponline/2016/07/15/world/europe/ap-eu-france-truck-attack-the-latest.html?_r=0)

• While cutting down on the most egregious polluters in any area comes with multiple local benefits — cleaner air, more efficient and cost-effective electricity production — the authors’ particular focus in conducting the study was helping to aid in global climate efforts.(https://www.washingtonpost.com/news/energy-environment/wp/2016/07/07/this-could-be-a-completely-different-strategy-for-tackling-the-worlds-carbon-emissions/)

Solution 1:

In both of the examples presented, "in" is an adverbial portion of a phrasal verb, a particle used in this instance to impart the case of the statement.

"To Aid in [something]" is in the dative case, while "To Aid [something]" is in the accusative.

Since cases in English are now vestigial, there is little difference in modern usage between the two.