Select the photo and select Break Shapes from the Arrange menu to separate the photo into four parts. Delete the top left square.

You should now have three separate square sections of the photo as shown on the right.

Using the Pen Tool, draw a horizontal and vertical line through the center of the square as shown.

Select the vertical line and the photo and select Combine Shapes > Subtract Shapes from the Arrange menu.

Select the horizontal line and the photo and Combine Shapes > Subtract Shapes again.