Learn Finnish: Kuulin lähetystä tutkittavan tullissa. - I heard that the shipment is being examined in customs.

This sentence uses the present passive referative construction to shorten an että (that) clause. Instead of starting a new clause with a passive verb (että ... tutkitaan), you use the present passive participle (tutkittava) and add the genitive -n ending to connect it back to the main verb kuulin.

How do you build the form tutkittavan from the dictionary form tutkia?

For Type 1 verbs like tutkia, the passive marker is -tta-. You add this to the verb stem along with the participle ending -va, creating tutkittava. Finally, add the -n ending required by the referative structure to get tutkittavan.

Why is lähetystä in the partitive case here?

It is the object of the examining action. The verb tutkia takes a partitive object because investigating or examining is considered an ongoing, continuous process. The object keeps its normal partitive case even when the sentence is compressed into this participle structure instead of a full clause.

Is it more common to use this structure or an että clause?

In everyday spoken Finnish, you will almost always hear the että clause instead: Kuulin, että lähetystä tutkitaan. The -tavan structure shown in this sentence is elegant and shorter, but it belongs mostly to formal written Finnish, official texts, and news broadcasts.