Can I do anything about a very long running KILL command?
First of all, thank you posting the DELETE query and the table layout
With regard to your question, there is nothing you can really do because a rollback is being done via the UNDO tablespace inside ibdata1 (it should have grown immensely). If you kill the mysqld process and restart it will just pickup where it left off as part of the crash recovery cycle.
Here is how you can handle large and small deletes in the future:
LARGE DELETEs
Instead of deleting 70% of the table and create lots of rollback info, try copying the tables you want to keep.
CREATE TABLE adc_fetched_documents_new LIKE adc_fetched_documents;
INSERT INTO adc_fetched_documents_new
    SELECT * FROM adc_fetched_documents
    WHERE id &gt; 73097292
;
ALTER TABLE adc_fetched_documents RENAME adc_fetched_documents_zap;
ALTER TABLE adc_fetched_documents_new RENAME adc_fetched_documents;
TRUNCATE TABLE adc_fetched_documents_zap;

Whenever, you delete 70% or more of the table, do it like this.
SMALL DELETEs
If you are deleting smaller chunks, perhaps you can do it with a DELETE JOIN:
CREATE TABLE deletion_ids (id INT NOT NULL PRIMARY KEY (id)) ENGINE=InnoDB;
INSERT INTO deletion_ids
    SELECT id FROM adc_fetched_documents
    WHERE id &lt;= 73097292
;
DELETE B.* FROM deletion_ids A INNER JOIN adc_fetched_documents B USING (id);

Give it a Try !!!