he was <present> at the scene

[WilliamTaft]

An example sentence of "deduce" in The Britannica Dictionary: They deduced that he was present at the scene of the crime.

What's the difference if I omit "present?"

 

[Amigos4]

What's the difference if I omit "present?"

You would have one less word in your sentence!

 

[Amigos4]

For me, the sentence works with or without the word "present".

 

[jutfrank]

The difference is in the register only. With present the sentence is more appropriate to whatever text, spoken or written, this is meant to be from. Part of that appropriacy is that the meaning is clearer too.

We can't comment very usefully on completely uncontextualised sentences.