it is my guess

[bosun]

When you guess, for example, someone may have stolen your friend's money, can I say

It's just my guess, but I suspect XX stole my money. However, don't jump into the conclusions. My guess can be wrong.

[susiedqq]

You can use that phrase, but it is usually used for casual times:

It's just my guess, but I think that flower is a rose.

Because you are talking about a serious or criminal act, there should be no "guesses". Try to back it up with some facts or observations.

I suspect XX stole my money. Here's why I came to that conclusion: He was the only one in the room alone with my wallet. He showed Fred that he had a lot of money. etc.

[esltutor]

It's just my guess, but I suspect XX stole my money. However, don't jump into the conclusions. My guess can be wrong.

"It's just my guess, but I suspect XX stole my money. However, don't jump to conclusions. My guess may/could be wrong."

I would perhaps say, "It's just a guess, but I suspect XX stole my money. However, I shouldn't jump to conclusions. I could be wrong."

In American English, we don't "jump into conclusions," but we do "jump to (any) conclusions."

Best,
Debra
http://www.teaching-esl-to-adults.com