sqlquery to get all cases in a child table

I have to tables - demographics and PatSubs.  Both tables are linked by caseno filed.

Now, PatSubs may have one or many substance entry for the caseno.

If I do the following:

USE [njpies2013]

GO

SELECT [CaseNumber]

     ,[CenterCode]

     ,[YearCode]

      ,[SubVerbatim]

 FROM [dbo].[ToxExpSub]

   where SubPoisindexCode = 6931087

GO

I will only get the cases in PatSub that match =693107; however what I want is if there's a record with PoisendexCode 6931087 than give me all the entries in PatSub for THAT caseno

Please help me with this query,

Thanks

Raul

Raul Rego